• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.521-526
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• 2016

This paper suggests a new design that makes use of rotary inertia that can allow autonomous movement of an autonomous colonoscope robot in the colon of a patient as a locomotive mechanism. As commercial colonoscopy causes a lengthy time of pain and discomfort to the patients when colonoscopy patients are reluctant to receive surgery, there is a tendency to avoid the test in the early diagnosis of colorectal cancer. To solve this problem, research has been conducted on the next generation of robotic colonoscopes that can reduce the discomfort and pain by moving autonomously within the colon of the patients. In the driving mechanism utilizing the rotational inertia, a flywheel is driven by a motor to store energy and produce rotational inertia. By the energy stored and released by the flywheel, the stick phenomenon that occurs when the robot is running in the intestine can be overcome effectively. To do this, a controller that can control the velocity of the flywheel and is robust to high frequency noise was designed and implemented. The driving mechanism using the rotational inertia presented here showed that the structure is also effective and the experiment can be run easily compared to another mechanism.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.62-69
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• 2017

This paper presents a methodology for evaluating the performance of wall-climbing robots. In the literature on wall-climbing robots, there is little information on indices and evaluation methods for consistent and exact performance. Because various types of wall-climbing robots can be developed with regard to adherence and locomotion, a general method of measuring their performance regardless of type is needed. Therefore, we propose two major performance indices-the vertical adhering weight and vertical climbing speed-and their stepwise evaluation procedures. To verify the effectiveness of the proposed method, we applied it to a hull-climbing robot that we previously developed. The target robot was evaluated to have a vertical adhering weight of 18.5 kg through a slip measurement procedure and a vertical climbing speed of 41 cm/s with a position control system.

• Journal of Trauma and Injury
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• v.30 no.2
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• pp.33-40
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• 2017

Purpose: The role for minimally invasive surgery in chest trauma is vague, one that recently is more frequently performed, and one attractive option to be considered. Thoracoscopic surgery may improve morbidity, mortality, hasten recovery and shorten hospital stay. Methods: A total of 31 patients underwent video assisted thoracoscopic surgery for the treatment of blunt and penetrating chest trauma from June 9th, 2013 to March 21st, 2016 in Jeju, South Korea. Results: Twenty-three patients were males and eight patients were females. Their ages ranged from 23 to 81 years. The cause of injury was due to traffic accident in 17 patients, fall down in 5 patients, bicycle accident in 2 patients, battery in 2 patients, crushing injury in 2 patients, and slip down, kicked by horse, and stab wound in one patient each. Video assisted thoracoscopic exploration was performed in the 18 patients with flail chest or greater than 3 displaced ribs. The thoracoscopic procedures done were hematoma evacuation in 13 patients, partial rib fragment excision in 9 patients, lung suture in 5 patients, bleeding control (ligation or electrocautery) in 3 patients with massive hemothorax, diaphragmatic repair in two patients, wedge resection in two patients and decortication in 1 patient. There was only one patient with conversion to open thoracotomy. Conclusion: There is a broad range of procedures that can be done by thoracoscopic surgery and a painful thoracotomy incision can be avoided. Thoracoscopic surgery can be done safely and swiftly in the trauma patient.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.453-461
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• 2013

Controlling the stick and slip motions of the contact lines in a confined geometry comprised of a spherical lens with a flat substrate is useful for manufacturing polymer ring patterns. We used a sphere on a flat geometry, by which we could control the interfaces of the solution, vapor and substrate. By this method, hundreds of concentric ring-pattern formations of a linear conjugated polymer, poly [2-methoxy-5-(2-thylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), were generated with excellent regularity over large areas after complete solvent evaporation. Subsequently, the MEH-PPV ring patterns played a role as a directed template to organize highly regular concentric rings of single-walled carbon nanotubes(SWCNTs); when a droplet of the SWCNT suspension in water was casted onto the prepared substrate, hydrophobic polymer patterns confined the water dispersed SWCNTs in between the hydrophilicized $SiO_2/Si$ substrate. As the solvent evaporated, SWCNT-rings were formed in between MEH-PPV rings with controlled density. Finally, we used a lift-off process to produce SWCNT patterns by the removal of a sacrificial polymer template with organic solvent. We also fabricated a field effect transistor using self-assembled SWCNT networks on a $SiO_2/Si$ substrate.

• The Journal of Advanced Prosthodontics
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• v.3 no.4
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• pp.196-203
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• 2011

PURPOSE. This study evaluated marginal fit of glass infiltrated alumina cores fabricated using two techniques and their marginal stability after firing cycles of veneering porcelain. MATERIALS AND METHODS. Fifteen standardized all-ceramic crowns were fabricated on a metal die using each technique: slip cast technique of VITA In-Ceram sprint Alumina (Group A as control) and plastic foil matrix technique of Turkom-Cera fused alumina core system (Group B). Copings were compared between groups and within groups at coping stage and after firing each layer of veneering porcelain. A device was used to standardize seating of copings on the metal die and positioning of the specimens under the microscope after each stage of fabrication. The specimens were not cemented and marginal gap was measured using an image analyzing software (Imagepro Express) on the photographs captured under an optical microscope. Two tailed unpaired 't test' was used to compare marginal gaps in two groups and one way ANOVA was used to analyze marginal distortion within each group at 95% confidence interval. RESULTS. The marginal gap was smaller at the coping stage in group B ($60+30{\mu}M$) than group A ($81+21{\mu}M$) with statistical significance. After firing of veneering porcelain the difference was insignificant. At the final stage, both groups exhibited lower mean marginal gaps than at the initial coping stage with the difference of $11.75{\mu}M$ for group A and $11.94{\mu}M$ for group B, but it was statistically insignificant due to high value of standard deviation. CONCLUSION. Within the limitations of this study, it was concluded that both techniques produced copings with comparable and acceptable marginal fit and marginal stability on firing veneering porcelain.

• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.58-67
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• 1996

This paper describes some computational results of various energy and environmental systems using Patankar's SIMPLE method. The specific topics handled in this study are jet bubbling reactor for flue gas desulfurization, cyclone-type afterburner for incineration, 200m tall stack for 500 MW electric power generation, double skin and heat storage systems of building energy saving for the utilization of solar heating, finally turbulent combustion systems with liquid droplet or pulverized coal particle. A control-volume based finite-difference method with the power-law scheme is employed for discretization. The pressure-velocity coupling is resolved by the use of the revised version of SIMPLE, that is, SIMPLEC. Reynolds stresses are closed using the standard $k-{\varepsilon}$ and RNG $k-{\varepsilon}$ models. Two-phase turbulent combustion of liquid drop or pulverized coal particle is modeled using locally-homogeneous, gas-phase, eddy breakup model. However simple approximate models are incorporated for the modeling of the second phase slip and retardation of ignition without consideration of any detailed particle behavior. Some important results are presented and discussed in a brief note. Especially, in order to make uniform exit flow for the jet bubbling reactor, a well-designed structure of distributor is needed. Further, the aspect ratio in the double skin system appears to be one of important factors to give rise to the visible change of the induced air flow rate. The computational tool employed in this study, in general, appears as a viable method for the design of various engineering system of interest.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.19-26
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• 2014

Concrete guide rail and median barrier are an attached RC member, however they are vulnerable to cracking due to slip form construction and large surface of member. In this study, causes and pattern of cracking are analyzed through assessment and NDT (Non-Destructive Technique) evaluation for concrete guide rail and median barrier on highway structure. For this work, analysis on drying shrinkage and hydration heat are performed considering installation period, and plastic shrinkage is also analyzed considering their environmental conditions. From the evaluation, plastic settlement around steel location, drying/ plastic shrinkage, and aggregate segregation are inferred to be the main causes of cracking in the structures. The crack causes and patterns are schematized and techniques of crack-control are suggested. Furthermore concrete guide rail/ median barrier in the bridge on the sea are vulnerable to cracking at early age so that special attentions should be paid at the stages of material selection and construction.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.477-481
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• 2014

Flexible electronics have been to the fore because it is believed that flexibility can add incredible value such as light weight and mobility into the existing electronic devices and create new markets of large-area and low-cost electronics such as wearable eletronics in near future. Offset printing processes are regarded as major candidates for manufacturing the flexible electronics because they can provide the patterning resolution of micron-size effectively in large-area. In view of mechanics, the most important viewpoint in offset printing is how to achieve the synchronized movement of two contact surfaces in order to prevent slip between two contact surfaces and distortion of the blanket surface during ink transfer so that the high-resolution and good-overlay patterns can be printed. In this paper, a novel low-cost measurement method of the synchronization error using the motor control output signals is proposed and the compensation method is presented to minimize the synchronization error.

• The Korean Journal of Elementary Counseling
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• v.4 no.1
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• pp.191-214
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• 2005

This study aimed to examine the effect of Cyber Group Counseling on the depression of internet addiction children in elementary school. In this study, the following questions were posed: How effective is the Cyber Group Counseling on the depression of internet addiction children? In this study, subjects were 24 students who got 14 points over in KAIS and got 11 points over in CDI among 245 of 5th, 6th grade students in Daegu and Chongdo Kyungbuk who did Internet addiction scale for Korean Adolescent(KAIS) and Children's Depression Inventory(CDI). They were divided into experimental group and comparative group. Subjects in experimental group practiced Cyber Group Counseling for 12 sessions(60 minutes per session) for 6 weeks. But the control group had no treatment during the period. During the experiment, 2 of each groups were left out. The counseling schedule and hor· to join the Cyber Group Counseling clinic were notified by e-mail. The Cyber Group Counseling was on every Monday and Thursday. The Cyber Group Counseling progressed by internet chatting, bulletin board, e-mail and a slip paper counsel. The collected data were analyzed with SPSS/PC+ (statistical package for the social science/personal computer) program and t -test. The findings of this study were as follows: First, the depression of internet addiction children who joined in Cyber Group Counseling was significantly reduced than the others. So, Cyber Group Counseling was proved one of the useful psychotherapy approach. Second, the subordinate of depression including behavioral disturbance and anhedonia was significantly reduced. Third, the subordinate of depression including the dysphoric mood, the self-deprecation and physiological symptoms was reduced. But it was not statistically significant.

• Steel and Composite Structures
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• v.36 no.1
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• pp.103-118
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• 2020

The static behavior of grouped large-headed studs (d = 30 mm) embedded in ultra-high performance concrete (UHPC) was investigated by conducting push-out tests and numerical analysis. In the push-out test, no splitting cracks were found in the UHPC slab, and the shank failure control the shear capacity, indicating the large-headed stud matches well with the mechanical properties of UHPC. Besides, it is found that the shear resistance of the stud embedded in UHPC is 11.4% higher than that embedded in normal strength concrete, indicating that the shear resistance was improved. Regarding the numerical analysis, the parametric study was conducted to investigate the influence of the concrete strength, aspect ratio of stud, stud diameter, and the spacing of stud in the direction of shear force on the shear performance of the large-headed stud. It is found that the stud diameter and stud spacing have an obvious influence on the shear resistance. Based on the test and numerical analysis results, a formula was established to predict the load-slip relationship. The comparison indicates that the predicted results agree well with the test results. To accurately predict the shear resistance of the stud embedded in UHPC, a design equation for shear strength is proposed. The ratio of the calculation results to the test results is 0.99.