• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.65-72
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• 1998

The BTA drilling chip is better for deep hole drilling than other self-piloting with pad drilling chips because the large length to diameter ratio allows a unique cutting force dispersion and better supplies the high pressure fluid. Therefore the BTA is useful for many tasks, such as coolant hole drilling of large scale dies, as well as tube seat drilling, which is essential for the heat exchanger, and variable component drilling for automobiles. Deep hole drilling has several significant problems, such as hole deviation, hole over-size, circularity, straightness, and surface roughness. The reasons for these problems, which often result in quality short comings, are an alignment of the BTA drilling system and the unbalance of cutting force by work piece and tool shape. This paper analyzes the properties through an experiment which com¬pared single-edge BTA drills with multiple-edge BTA drills, as well as the shapes of the tools to cause an unbalance of cutting force, and its effect on the precision of the worked hole. Conclusions are as follows. 1) In SMSSC drilling, 60m/min of BTA with single and multi-edged tools proved the best cutting condition and the lowest wear character. 2) The roundness got a little worse as cutting speed was increased, but surface roughness was hot affected. 3) It was proved that the burnishing torque of both drills approached 26%. which is almost the same as the 24% insisted on by Griffiths, and the dispersion characteristic of the multi-edged BTA drill proved better than the single-edge BTA drill.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.127-133
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• 2013

PURPOSES : The impact performance of flexible barrier system such as structural response, vehicular motion and occupant safety vary depending on the impact point. Thus, to properly evaluate the performance of a flexible barrier system, impact should be made to a point which will lead to the worst possible results. This point is called the Critical Impact Point (CIP). This paper presents the way to determine the CIP for a SB2 class flexible barrier system which is consisted of Thrie-Beam rail and circular hollow tube post of 2m span. METHODS: Barrier VII simulations were made for impact points; Case 1 at a post, Case 2 at 1/3 span downstream from a post, Case 3 at middle of the span, Case 4 at 2/3 span downstream from a post. For the structural performance (deflections), impact simulation of 8000kg-65km/h-15degree was used, and for vehicle motion and occupant safety, simulation of 1300kg-80km/h-20degree impact was made and analysed. RESULTS: Case 1 gave the largest dynamic deflection of 75.72cm and also gave the largest snag value of 44.3cm. Occupant safety and exit angle of the vehicle after the impact were not sensitive to the impact point and were all below the allowable limit. CONCLUSIONS : For the SB2 class flexible barrier system's CIP can be regarded as a post which is sufficiently away from the end of Length of Need in order to avoid the end-effect of the barrier system. It can be more economic in the long run because the normal concrete pavement material is likely to cost more due to higher probability of maintenance and repair and higher social cost due to traffic accident, etc.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.471-479
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• 2002

In this paper, 18 square CFT columns filled with high-strength concrete were tested under concentric or eccentric axial loading. Two parameters of the experimental program included the buckling length-section depth ratio ($L_K$/D) and the eccentricity of the appled compressive load (e). In additon, mechanical properties such as the compressive concrete strength and compressive and tensile steel strength were measured and incorporated into the material models for the stress-strain relationships of concrete and steel. This model was used in an elasto-plastic analysis in order to predict the behavior of the slender CFT columns. Observtions of the failure mode during the tests under axial loadig were also presented. The strengths obtained from the analysis. Recommendations for Design, and Constructions of CFT structures were presented, as verified by the experimental results.

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.367-373
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• 2012

We fabricated a fiber-optic alpha/beta detector, which is composed of a sensing probe, a plastic optical fiber, a photomultiplier tube, and a multichannel analyzer, to obtain the energy spectra of radioactive isotopes. As inorganic scintillators of a sensing probe, a ZnS(Ag) film was coupled with a $CaF_2$(Eu) crystal for alpha and beta spectroscopy. In this study, $^{210}Po$ and $^{90}Sr$ were used as alpha and beta sources, respectively, and we measured the radiation energy spectra using a fiber-optic alpha/beta detector to identify alpha and beta emitting radionuclides for nuclear medicine application. Also, the variations of energy spectrum were obtained according to the length of plastic optical fiber.

• Child Health Nursing Research
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• v.18 no.1
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• pp.9-18
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• 2012

Purpose: This study was conducted to analyze factors affecting readmission of children with home ventilator care. Methods: To collect patient data, a retrospective chart review was done of medical records of children admitted between June 1, 2007 and May 31, 2010 at one children's hospital located in Seoul. During that period 30 children were discharged with a home ventilator. Results: Twenty-one of these children had a total of 63 readmissions during the study period, averaging 2.1 readmissions per child with a mean duration of hospitalization of 7.4 days. Children with nasogastric tubes were more frequently readmitted (t=7.232, p=.012) and duration of hospitalization was significantly longer (t=4.761, p=.038). Children who had cardio-pulmonary comorbidity were more frequently readmitted and had longer hospitalization than children without comorbidity (t=5.444, p=.027). When home ventilator assisted children were admitted via emergency room, they were hospitalized longer (t=14.686, p=<.001). Cardio-pulmonary morbidity and readmission via ER explained 38.1% of variation for readmission. Feeding method explained 15.0% of variation in length of hospitalization. Conclusion: The results suggest that health care providers must give individualized education on home ventilator care to parents with children who are at risk for readmission due to cardio-pulmonary comorbidities, nasogastric tube, or readmission via ER.

• Journal of Korean Academy of Nursing
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• v.49 no.6
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• pp.724-735
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• 2019

Purpose: This study was conducted to investigate relationship between delirium, risk factors on delirium, and patient prognosis based on Donabedian's structure-process-outcome model. Methods: This study utilized a path analysis design. We extracted data from the electronic medical records containing delirium screening data. Each five hundred data in a delirium and a non-delirium group were randomly selected from electronic medical records of medical and surgical intensive care patients. Data were analyzed using SPSS 20 and AMOS 24. Results: In the final model, admission via emergency department (Β=.06, p=.019), age over 65 years (Β=.11, p=.001), unconsciousness (Β=.18, p=.001), dependent activities (Β=.12, p=.001), abnormal vital signs (Β=.12, p=.001), pressure ulcer risk (Β=.12, p=.001), enteral nutrition (Β=.12, p=.001), and use of restraint (Β=.30, p=.001) directly affecting delirium accounted for 56.0% of delirium cases. Delirium had a direct effect on hospital mortality (Β=.06, p=.038), hospital length of stay (Β=5.06, p=.010), and discharge to another facility (not home) (Β=.12, p=.001), also risk factors on delirium indirectly affected patient prognosis through delirium. Conclusion: The use of interventions to reduce delirium may improve patient prognosis. To improve the dependency activities and risk of pressure ulcers that directly affect delirium, early ambulation is encouraged, and treatment and nursing interventions to remove the ventilator and drainage tube quickly must be provided to minimize the application of restraint. Further, delirium can be prevented and patient prognosis improved through continuous intervention to stimulate cognitive awareness and monitoring of the onset of delirium. This study also discussed the effects of delirium intervention on the prognosis of patients with delirium and future research in this area.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.506-509
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• 2002

An optical system for a stereoscopic video recorder is designed with the field of view 42$^{\circ}$ and effective diameter 22 mm. We can use it by attaching it to the front lens of any video camera or camcorder to record a stereoscopic scene. This system is a double Kepler type afocal system to make the image erect and a bi-ocular type to record and display the stereoscopic scene. The optical tube length is folded with several flat mirrors and a beam splitter to be compact. This optical system is composed of 4 groups of lenses and each group serves as a relay lens for minimizing the vignetting effect. Whole field stereoscopic scenes may be captured by perpendicularly polarized alternated recording with a chopper and two perpendicular polarizers, without any loss of light energy. The displayed images may be seen stereoscopically with polarized spectacles and are kinetic because of an afterimage effect.

• Journal of Digital Convergence
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• v.11 no.3
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• pp.95-100
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• 2013

K-POP is getting population at the all over the world. K-POP is based on the hook song that made using repetitive lyrics and melody. The characteristics of the music is a bit simple and cheerful rhythm and melody easy to sing along, interesting lyrics and great dance skills. K-POP is spreading to various countries via various social networking services such as YouTube, Facebook, Twitter. K-POP dominated by the digital music market, showed a growing tendency to shorten the length of music, to create a music that can give a strong impression. And 60 second pre-listening function increased music used the chorus in the first part. But it was generated the result that made obscures the configuration of the music and the meaning of the lyrics. In this paper, we study the characteristics of K-POP music and will present three directions of the hook song music production. Finally, we compared to Kangnamstyle of Psy using the proposed three standards.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.4
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• pp.213-220
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• 2020

In the present paper, implosion responses of two adjacent cylindrical tubes under external hydrostatic pressure were experimentally investigated. The cylinder models were fabricated of aluminium alloy 6061-T6 commercial tubes. In the experiment, a pair of two-cylinders were placed inside of a support frame in a medium-size pressure chamber, whose design pressure was 6.0MPa. The distance between the two-cylinders was 30 millimeter measured from outer shell at the mid-length. The implosion tests were performed with water and compressed nitrogen gas as the pressurizing media. The ambient static pressure of the chamber and local dynamic pressure near the two-imploded models were measured simultaneously. It was found that the energy released during an implosion from the first, weaker cylinder triggered the instability of the second, stronger cylinders. In other words, the resulting shock wave of the first implosive impact from the weaker cylinder could cause the premature failure of the neighboring stronger cylinders. The non-contact implosion phenomena from the two-cylindrical tube were clearly observed.

• Journal of the Korean Magnetics Society
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• v.13 no.6
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• pp.251-256
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• 2003

We have developed the quality analysis system for magnetic field effect of cathode-ray tube that is used a monitor, TV and medical appliance. We designed and constructed the large 3-axis square coil (2 m length) system for the generation of 3-component magnetic field using power supply, magnetometer and computer below 0.2 mT range. The coil constant is 30.31 ${\mu}$T, 29.73 ${\mu}$T and 30.51 ${\mu}$T for the X, Y and Z axis square coil respectively. The magnetic field resolution was 0.01 T. The uniformity of magnetic field was measured within 1 ％ in the range of 12 cm.