• Explosives and Blasting
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• v.42 no.2
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• pp.29-41
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• 2024

The increasing demand for metallic minerals due to global growth and the continued exploitation of near-surface minerals requires safe and efficient ways to mine ores present in deep mines. In deep mines, stresses concentrated around the cavity increase, which can lead to problems such as induced seismicity and rockbursts. In addition, the transfer of energy from blasting to deeply located faults can cause fault slip, which can lead to earthquakes, and controlling these events is key to deep mining methods. In this technical report, we will introduce the Underhand Closed Bench (UCB) mining method, which can control possible accidents and increase productivity when mining in deep mines.

• Archives of Craniofacial Surgery
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• v.13 no.2
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• pp.104-110
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• 2012

Purpose: Who may dare to state that optimal choice of treating nasal bone fracture is closed reduction? Few decades of authors' experience in nasal bone fracture has lead to believe that more active and assertive approach in nasal bone fracture by performing simultaneous lateral osteotomy may be applied in proper indications to acquire more accurate reduction and cosmetically satisfying result. Methods: From May 2008 to October 2009, among 241 nasal bone fracture patients, 20 patients underwent simultaneous lateral osteotomy with nasal bone fracture reduction. Followed by rigid septal correction, nasal cavity is packed to stabilize the fracture segment for safer osteotomy. Through intranasal incision, in selected cases of difficult reduction or for cosmetic purposes, various types of lateral osteotomy was performed corresponding to the fracture anatomy, conditions of the nasal cavity. Postoperative nasal packing was retained for one week and nasal dorsum splint for 3 weeks. Results: Lateral osteotomy was utilized for difficult cases of closed reduction, for correction of wide nose, hump and deviation in 9, 5, 2, and 4 cases, respectively. Patient satisfaction was scaled 90% in satisfaction and moderate in 10% (2 cases), complaining of mild nasal tip deviation. Physicians detected 2 cases of apparent deformity with patient recognition; one patient with mild step deformity at the osteotomy site and the other patient with minimal implant mobility. Conclusion: By accompanying profound understanding of the fracture anatomy, more active and assertive approach in nasal fracture reduction can be coincide with simultaneous lateral osteotomy to reduce the rate of secondary deformity and to obtain more cosmetically satisfying result.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.459-468
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• 2021

In patients with myasthenia gravis, it is difficult to manufacture and maintain dentures because the muscles and nervous system in the oral cavity are not properly adjusted. In addition, excessively extended or thick dentures may cause muscle weakness by stimulating the muscles, so dentures should be manufactured in consideration of this. In this case, a denture was fabricated using the closed mouth technique in a patient with myasthenia gravis with mouth opening limitation. Using the closed mouth technique, the patient's masticatory pressure and muscle movements were reproduced and denture with good retention were manufactured.

• Archives of Craniofacial Surgery
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• v.22 no.6
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• pp.319-323
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• 2021

Background: Prophylactic antibiotics are used to prevent surgical wound infection; however, proper indications must be followed with careful consideration of the risks and benefits, especially in clean or clean-contaminated wounds. Nasal bone fractures are the most common type of facial bone fracture. The most common method for treating nasal bone fracture is closed reduction, which is performed inside the nasal cavity without an incision. The purpose of this study was to determine the need for antibiotic use in the closed reduction of nasal bone fractures. Methods: A retrospective study was conducted using data from the National Insurance Service Ilsan Hospital of the Republic of Korea between 2016 and 2018. The records of patients who underwent closed reduction of nasal bone fracture were reviewed and classified according to sex, age, comorbidities, perioperative antibiotic usage, postoperative complications, nasal packing, anesthesia type, surgeon's specialty, and operation time. Results: Among the 373 patients studied, the antibiotic prescription rate was 67.3%. Just 0.8% of patients were prescribed preoperative antibiotics only, 44.0% were prescribed postoperative antibiotics only, and 22.5% were prescribed both preoperative and postoperative antibiotics. There were no cases that satisfied the definition of "surgical site infection." Furthermore, 2.1% of infection-related complications (e.g., mucosal swelling, synechia, and anosmia) occurred only in the antibiotic usage group. The use of nasal packing, anesthesia type, and surgeon's specialty did not show any difference in infection-related complication rates. Conclusion: According to the study findings, the routine use of perioperative antibiotics is not recommended in uncomplicated nasal bone fracture surgery.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1071-1075
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• 2003

In a closed square cavity filled with a liquid, a cooled the upper horizontal wail and a heated the lower horizontal wall, the flow isn't generated under the ground-based condition when Rayleigh number is lower than 1700. In such case the flow phenomena near an air bubble under a cooled horizontal wall were investigated. The temperature and the flow fields were studied by using the Thermo-sensitive Liquid-Crystal and the image processing. The qualitative analysis for the temperature and the flow fields were carried out by applying the image processing technique to the original data. Injecting bubble at the center point of upper cooled wall, the symmetry shape of two vortexes near an air bubble was observed. The bubble size increased, the size of velocity and the magnitude of velocity increased. In spite of elapsed time, a pair of two vortexes was the unique and steady-state flow in a square cavity and wasn't induce to the other flow in the surround region.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.600-606
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• 2008

In closed-die hot forging, a billet is formed in dies such that the flow of metal from the die cavity is restricted. Some parts can be forged in a single set of dies, whilst others, due to shape complexity and material flow limitations, must be shaped in multi sets of dies. The purpose of a performing operation is to distribute the volume of the parts such that material flow in the finisher dies will be sound. This study focused on the design of preforms, flash thickness and land width by theoretical calculation and finite element analysis, to manufacture the super hot forging product, 70MC type piston crown used in marine engine. The optimal design of preforms by the finite element analysis and the design experiment achieves adequate metal distribution without any defects and guarantees the minimum forming load and fully filling of the cavity of the die for producing the large piston crown. The maximum loads obtained by finite element analysis are compared with the results of experiments. The loads of the analysis have good agreements with those of the experiment. Results obtained using DEFORM-2D enable the designer and manufacturer of super hot forging dies to be more efficient in this field.

• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.323-327
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• 2003

This study has been conducted to compare the efficacy of sodium carboxymethylcellulose (SCMC) and hyaluronic acid (HA) on prevention of adhesion after artificial wound was induced in intestine. 1 % SCMC and 0.3% HA solution and saline solution were respectively administered to abdominal cavity. Each of the three groups consists of 11 rats. The abdominal cavity of each rat was coated with 2 ml of the allocated solution just after the abdomen was cut open, and it was coated with each solution of 1 ml before abrasion were caused on the cecum, the ascending colon and the transverse colon. Then, an additional 1 ml solution was injected before the abdomen was closed. On day 14 after the operation, each adhesion formation was evaluated at the score of 0-4. The HA group and SCMC group showed significantly lower adhesion scores than control group in all regions(P< 0.05). The adhesion scores of ascending colon, transverse colon and no abrasion region of the viscera showed little difference between HA group and SCMC group(P< 0.05), but the effect of adhesion reduction showed higher tendency in the HA group than the SCMC. The adhesion score of the cecum was significantly lower in HA group than SCMC group(P< 0.05). In conclusion, the SCMC solution and HA solution were effective on prevention of abdominal adhesion resulting from the celiotomy. Among of them, the HA solution could be more effective on prevention of adhesion than SCMC solution.

• Multiscale and Multiphysics Mechanics
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• v.1 no.3
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• pp.225-231
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• 2016

The formation of silicon-on-nothing (SON) structure during an annealing process from the silicon substrate including the trench structures has been considered as an effective technique to construct the structure that has an empty space under the closed flat surface. Previous studies have demonstrated the mechanism of the formation of SON structure, which is based on the surface diffusion driven by the minimization of their surface energy. Also, it has been fragmentarily shown that the morphology of SON structure can be affected by the initial design of trench (e.g., size, number) and the annealing conditions (e.g., temperature, pressure). Based on the previous studies, here, we report a comprehensive study for the design of the cavity-embedded structure (i.e., SON structure). To do this, a dynamic model has been developed with the phase field approach. The simulation results represent that the morphology of SON structures could be detailedly designed, for example the position and thickness of cavity, the thickness of top and bottom layer, according to the design parameters. This study will give us an advantage in the effective design of SON structures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.199-203
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• 1995

The technology of Semi-Solid Forging (SSF) has been actively developed to fabricate near-net- shape products using light and hardly formable materials, the SSF process is composed of slug heating, forming, compression holding and ejecting step. After forming step in SSF, the slug is compressed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. The compression holding time that can affect mechanical properties and shape of products is important to make decision, where it is necessary to find overall hert transfer coefficeient properly which has large effect on heat transfer between slug and die. This paper presents the procedure to predict compression holding time of octaining the final shaped part with information of temperature and solid fraction for a cylindrical slug at compression hoiding step in closed-die compression process using heat transfer analysis considering latent heat by means of finite element method. The influence of the predicted compression hoiding time on mechanical properties of products is finally investigated by experiment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.26-30
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• 2003

Since the dimension of cold forged part is larger than the cavity size of forging die, the difference results from the various features, such as, the elastic characteristics of die and workpiece, thermal influences, and machine-elasticity. All of these factors should be considered to get more accurate prediction of the dimension of forged part. In this paper, severe FE techniques are proposed to improve the prediction accuracy of dimension for cold forged part. To validate the importance of the above mentioned factors, and the estimated results are compared with the experimental results. The used model is a closed die upsetting of cylindrical billet. The calculated dimensions are well coincided with .the measured values based on the proposed techniques. The proposed techniques have put two simple but important points into Fe simulation. One is the separation of forging stages into 3 steps, from a loading through punch retraction to ejecting stage. The other is the dimensional change, according to the temperature changes due to the deformation. The FE analysis could predict the dimension of cold forged part within the $10{\mu}m$, based on the more realistic consideration.