• Design & Manufacturing
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• v.17 no.4
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• pp.72-78
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• 2023

Injection molding is a process widely used in various industries because of its high production speed and ease of mass production during the plastic manufacturing process, and the product is molded by injecting molten plastic into the mold at high speed and pressure. Since process conditions such as resin and mold temperature mutually affect the process and the quality of the molded product, it is difficult to accurately predict quality through mathematical or statistical methods. Recently, studies to predict the quality of injection molded products by applying artificial neural networks, which are known to be very useful for analyzing nonlinear types of problems, are actively underway. In this study, structural optimization of neural networks was conducted by applying multi-task learning techniques according to the characteristics of the input and output parameters of the artificial neural network. A structure reflecting the characteristics of each process step was applied to the input parameters, and a structure reflecting the quality characteristics of the injection molded part was applied to the output parameters using multi-tasking learning. Building an artificial neural network to predict the three qualities (mass, diameter, height) of injection-molded product under six process conditions (melt temperature, mold temperature, injection speed, packing pressure, pacing time, cooling time) and comparing its performance with the existing neural network, we observed enhancements in prediction accuracy for mass, diameter, and height by approximately 69.38%, 24.87%, and 39.87%, respectively.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.253-258
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• 2010

In the field of the $CO_2$ absorption process using aqueous ammonia, the effects of regeneration pressure and temperature on $CO_2$ absorption performances of the aqueous ammonia were investigated. The absorbents were prepared by dissolving ammonium carbonate solid in water to grant the resulted solution 0.5 $CO_2$ loading ($mol\;CO_2/mol\;NH_3$) and various ammonia concentration (14, 20, 26 and 32 wt%). As-prepared absorbents were regenerated at high pressure and temperature (over $120^{\circ}C$ and 6 bar) before the absorption test. The absorption test was carried out by injecting the simulated gas that contains 12 vol% of $CO_2$ into a bubbling reactor. The introduction of 26 wt% of the ammonia concentration for $CO_2$ absorption test resulted in the higher absorption capacities than other experimental conditions. In particular, when the absorbents with 26 wt% of the ammonia were regenerated at $150^{\circ}C$ and 14 bar, the highest absorption capacity, $45ml\;CO_2/g$, was obtained. According to the analysis of absorbents using acid-base titration, the ammonia loss during the regeneration of the absorbents with a fixed ammonia concentration decreased as the regeneration pressure increased, while it increased as the regeneration temperature increased. In the condition of fixed regeneration pressure and temperature, as expected, the ammonia loss increased as the ammonia concentration increased. The measured $CO_2$ loadings and ammonia concentrations of absorbents were compared to the values calculated by Electrolyte NRTL model in Aspen Plus.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.101-114
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• 2008

Pressurized grouting is a common technique in geotechnical engineering applications to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressurized grouting has been applied to a soil-nailing system which is widely used to improve slope stability. Because interaction between pressurized grouting paste and adjacent ground mass is complicated and difficult to analyze, the soil-nailing design has been empirically performed in most geotechnical applications. The purpose of this study is to analyze the ground behavior induced by pressurized grouting paste with the aid of laboratory model tests. The laboratory tests are carried out for four kinds of granitic residual soils. When injecting pressure is applied to grout, the pressure measured in the adjacent ground initially increases for a while, which behaves in the way of the membrane model. With the lapse of time, the pressure in the adjacent ground decreases down to a value of residual stress because a portion of water in the grouting paste seeps into the adjacent ground. The seepage can be indicated by the fact that the ratio of water/cement in the grouting paste has decreased from a initial value of 50% to around 30% during the test. The reduction of the W/C ratio should cause to harden the grouting paste and increase the stiffness of it, which restricts the rebound of out-moved ground into the original position, and thus increase the in-situ stress by approximately 20% of the injecting pressures. The measured radial deformation of the ground under pressure is in good agreement with the expansion of a cylindrical cavity estimated by the cavity expansion theory. In-situ test revealed that the pullout resistance of a soil nailing with pressurized grouting is about 36% larger than that with regular grouting, caused by grout radius increase, residual stress effect, and/or roughness increase.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.442-449
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• 2017

In this study, a method to inject small amount of activation agent from the outside of the pipeline to the inside wall of the pipe was newly proposed to enhance pumping efficiency of cementitious materials. The activation agent is injected into the slip-layer, which is generally formed in the vicinity of the inside wall of the pipe during pumping cementitous materials. Through the injections, it is expected to decrease viscosity of slip-layer, namely, the friction between the mateirals and the pipe. The proposed method was verified by lab-scale pumping tests with mortars having water to cement ratio of 47%. The tests were performed with two different type of activation agents(superplasticizer and anionic surfactant) and three different amount of the agents(0.14, 0.28, 0.42% of the mortar volume). The compressive strength were measured with and without injecting the activation agent, and the internal pressures of pipeline were measured. When the anionic surfactant was used, there was no change in the compressive strength. As the amount of anionic surfactant increased, the pumping pressure decreased up to 71.4% at the maximum.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.74-79
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• 2017

The fire extinguishing performance of hybrid nozzle systems is improved by injecting an extinguishing agent concentrically into the target site and, in this study, water mist is used as a water curtain to confine the droplets of the agent. In this study, we numerically investigated the effect of the foundation angle and injection pressure on the performance of a hybrid nozzle by evaluating the mean radius of the volume fractions of the agent and water mists. An experiment involving a water mist nozzle was carried out to validate the numerical method and then the droplet behaviors, e.g., stochastic collision, coalescence and breakup, were calculated with 2-way interaction Discrete Particle Modeling (DPM) in the steady state for the hybrid nozzle system. The mean radius of the water mists increased by about 40 %, whereas that of the agent decreased by about 21 %, when the injection pressure was increased from 30 bar to 60 bar. In addition, the mean radius of the agent increased by about 24 % as the foundation angle of the hybrid nozzle head increased from $30^{\circ}$ to $60^{\circ}$. As a result, it can be inferred that the injection angle and pressure are important factors for hybrid water mist designs.

• Journal of the Korean GEO-environmental Society
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• v.15 no.5
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• pp.23-29
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• 2014

So far, the grouting using pressure injection has been extensively used to avoid adverse effects such as soil disturbance. Whereas, the pressure injection to the limitations of the diffusion range, so that the kinks would last injection of cement particles by introducing a frequency oscillation effect improved injection method have been recently developed. In this study, a pilot test was performed to compare injection effects of the both methods. The injections using both methods were tested on the embankment which consists of core clay and weathered soil. Subsequently, the injected volume, SPT N values, in-situ permeability and electrical resistivity were measured to compare their effects. The vibration method showed more effective permeation comparing with the pressure method. Also, it showed more homogeneously improved ground than the existing method. For SPT results, the vibration method presented increase of mean N value as much as 17.4 % comparing with the conventional method. Higher electrical resistivity was presented in case of injecting with vibration method and it indicated the injection was extensively completed. Finally, it is expected that the economic feasibility will be improved by decrease of drilling spacing, when the existing method is replaced with vibration method.

• Journal of Veterinary Clinics
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• v.25 no.6
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• pp.488-493
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• 2008

This study compared the effect of injectable combinations of anesthetics on each of the fluorescein angiographic phases in order to determine the most useful anesthetic combination for the procedure. Acepromazineketamine (AK), xylazine-ketamine (XK), diazepam-ketamine (DK) and zolazepam-tiletamine (ZT) group were administered randomly to 8 dogs with a two-week interval between different combination doses. The vital signs including the heart rate and arterial pressure were measured before anesthesia and every five minutes during anesthesia. Serial angiographic images were obtained after injecting a sodium fluorescein dye (25 mg/kg) and the onset time of arterial phase (AP), arteriovenous phase (AVP), early venous phase (EVP) and late venous phases (LVP) were recorded. The onset time of the AP, AVP and EVP were significantly slower in the AK and XK groups than in the DK and ZT groups. The total duration of the AP and AVP in the AK group was significantly longer than those in the ZT group. The heart rates were significantly higher in the DK and ZT groups. The arterial pressure was significantly higher in the AK and XK groups (p<0.05). There were significant differences in each angiographic onset time and duration depending on the changes in the heart rates and arterial pressure. The AK and XK groups showed a long angiographic duration allowing an accurate evaluation. Overall, it is believed that AK and XK are more useful for performing fluorescein retinal angiography than DK and ZT.

• Journal of the Korean GEO-environmental Society
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• v.3 no.1
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• pp.47-55
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• 2002

The slope reinforcing method utilized in this paper reinforces the ground overall by means of filling borehole as well as permeating grout material into ground by injecting it through the grouting pipe. In order to reflect these characteristics to design, not only the ground reinforcing effect by the structural material itself but also the ground strength improvement effect by the grouting injection must be quantitively evaluated. But precedent research of it has been insufficient. Therefore, the slope reinforcing method was applied to the weathered rockmass slope situated in the highway in order to analyze reinforcing effect and the instrumentation of slope was performed. Through analysis of this field test, the slope reinforcing method was proved to be effective and back analysis method based on instrumentation values of slope was proposed to apply to reinforcing design. In this paper, the effectiveness of reinforcing method was certified through proposed back analysis.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.120-123
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• 2006

Spontaneous extensor pollicis longus tendon rupture is commonly caused by attrition of the tendon from trauma or inflammatory processes. We experienced a patient with extensor pollicis longus tendon rupture after steroid injection, in which the rupture may have been caused by the effects of steroid itself as well as direct damage from the needle. A 51-year-old woman complained of inability to extend her right thumb at the first metacarpophalangal & interphalangeal joint level. The patient had a history of local steroid injection into the dorsal & radial side of wrist on two occations, and had no history of trauma or rheumatologic disease. After a physical examination of the patient, we decided to explore the wrist. The patient agreed with operation. Intraoperatively, an incision was made into the wrist and the proximal and distal ends of the ruptured extensor pollicis longus tendon were identified. The defect between the proximal and the distal end was measured to approach 8cm, and a palmaris longus tendon graft was performed. After three months of rehabilitation, the first metacarpophalangal & interphalangeal joint recovered the normal range of motion. Steroid injection has been widely used in various musculoskeletal disorders such as rheumatoid arthritis and osteoarthritis. However, inadvertent steroid injection into the extra or intra articular spaces may lead to tendon rupture. Steroids reduce tensile strength by decreasing tenocyte activity and collagen synthesis. Also, the physical effect of direct needle-stick injury into the mesotenon and blood vessels around the tendon may cause damage. In addition, hematoma and edema may increase pressure around the tendon and compromise blood supply, leading to tendon degeneration and subsequent rupture. When injecting steroid into an articular area, all physicians should have a complete understanding of the surrounding anatomy and always keep in mind the hazards of such procedures.

• The Korean Journal of Pain
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• v.1 no.2
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• pp.164-170
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• 1988

Neurolysis of the celiac plexus is performed to relieve intractable pain caused by carcinoma of the stomach, liver and pancreas, and upper abdominal metastasis of tumors having more distant origins. It is also occasionally effective in controlling the pain of chronic pancreatitis. Alcohol celiac plexus blocks were done in 22 patients of whom 18 had intractable upper abdominal pain from cancer and 4 had pain from chronic pancreatitis. In most cases, an initial diagnostic block with 0.2 percent bupivacaine was followed by the therapeuntic block performed by injecting 50ml of 60 percent ethyl alcohol. Good to excellent pain relief occurred in 86 percent of patients. Duration of pain relief was from 4 months to 7 months in 55 percent of patients. Complications and side effects were infrequently seen but did include a 16 percent decrease of mean systolic arterial pressure and 16 cases of facial flushing. This block is remarkably safe as well as effective for the relief of upper abdominal pain from cancer origin.