• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.269-273
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• 2014

The objective of this study is to safety assessment for human body on the guided missile combustion products. This study is to verify the safety assessment when operating the interior missile ejection take on verify the safety of the human body. During the missile ejection of combustion products, this study is analyzed combustion products. Result are accepted NIOSH and KOSHA of the safe guideline, and 6 exposure gas to the specified values 42% (CO), 22% ($CO_2$), not detected (others) are within minimal exposures criteria of the reference value respectively. Contribution of these results supported that interior missile ejection during combustion products may have been ensured human safely. Therefore, the future for improving the environmental safety of the shooting projectile steel plate round, dust collector, ventilation and other facilities is to improve environmental safety and efficient renovated design needed by target focused areas.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.599-608
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• 2018

This study investigates the feasibility of adopting the results of the UC (unconfined compression) test to assess the total cohesion of the unsaturated soil. A series of laboratory tests were conducted on samples of unsaturated lateritic soils of northern Taiwan. Specifically, the unconfined compression test was combined with the pressure plate test to obtain the unconfined compression strength and its matric suction of the samples. Soil samples were first compacted at designated water content and then subjected to the wetting process for saturation and the subsequent drying process to its target suction using the apparatus developed by the authors. The correlations among the matric suction, the unconfined compression strength and the total cohesion were studied. As a result, a simplified method to estimate the total cohesion using the unconfined compressive strength is suggested. The calculated results compare reasonably with the unsaturated triaxial test results. Current results show good performance; however, further study is warranted.

• Steel and Composite Structures
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• v.39 no.5
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• pp.645-664
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• 2021

There is a growing need of seismic retrofit of existing non-seismically designed structures in Korea after the 2016 Gyeongju and 2017 Pohang earthquakes, especially school buildings which experienced extensive damage during those two earthquakes. To this end, a steel multi-slit damper (MSD) was developed in this research which can be installed inside of partition walls of school buildings. Full-scale two-story RC frames were tested with and without the proposed dampers. The frames had structural details similar to school buildings constructed in the 1980s in Korea. The details of the experiments were described in detail, and the test results were validated using the analysis model. The developed seismic retrofit strategy was applied to a case study school building structure, and its seismic performance was evaluated before and after retrofit using the MSD. The results show that the developed retrofit strategy can improve the seismic performance of the structure to satisfy a given target performance level.

• Transactions of Materials Processing
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• v.31 no.2
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• pp.96-102
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• 2022

The multi-point dieless forming technology is one of flexible forming technologies that can form 3D curved surfaces of various shapes utilizing a lot of punch arrangements. A new technology that can simultaneously apply high-temperature forming and flexible forming technology by fusing local heating effect to such multi-point dieless forming technology was proposed in the present study. A simple local heating multi-point dieless forming apparatus was fabricated to confirm the applicability of this new technology. This equipment was designed to be used as a heat source by inserting heating cartridges in the head of the multi-point punch. Cartridges were used for all individual punches. Using the manufactured equipment, the time to raise the temperature to the target temperature and the surface temperature of the punch head part in contact with the plate were measured. In addition, forming experiments were carried out according to sheet material temperature (100 ℃, 200 ℃, and 300 ℃) to obtain forming results for each condition. The applicability and feasibility of this technology were confirmed through experimental results.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.137-143
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• 2013

Purpose: We are to find out the difference of calculated dose of treatment planning system (TPS) and measured dose in case of inhomogeneous organ structure. Materials and Methods: Inhomogeneous phantom is made with solid water phantom and cork plate. CT image of inhomogeneous phantom is acquired. Treatment plan is made with TPS (Pinnacle3 9.2. Royal Philips Electronics, Netherlands) and calculated dose of point of interest is acquired. Treatment plan was delivered in the inhomogeneous phantom by ARTISTE (Siemens AG, Germany) measured dose of each point of interest is obtained with Gafchromic EBT2 film (International Specialty Products, US) in the gap between solid water phantom or cork plate. To simulate lung cancer radiation treatment, artificial tumor target of paraffin is inserted in the cork volume of inhomogeneous phantom. Calculated dose and measured dose are acquired as above. Results: In case of inhomogeneous phantom experiment, dose difference of calculated dose and measured dose is about -8.5% at solid water phantom-cork gap and about -7% lower in measured dose at cork-solid water phantom gap. In case of inhomogeneous phantom inserted paraffin target experiment, dose difference is about 5% lower in measured dose at cork-paraffin gap. There is no significant difference at same material gap in both experiments. Conclusion: Radiation dose at the gap between two organs with different electron density is significantly lower than calculated dose with TPS. Therefore, we must be aware of dose calculation error in TPS and great care is suggested in case of radiation treatment planning on inhomogeneous organ structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3626-3632
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• 2010

Some design changes were made to enhance the uniformity of temperature distribution inside the chamber of semiconductor test equipment. The design changes include the installation of adjustable airflow controller inside the chamber, the alignment of the centers of heater and match plate, the change in the size and the shape of holes in match plate base, and the addition of new holes of 2 mm diameter in order to allow airflow directly to the temperature sensors. In order to verify their effects, the temperature distributions inside the chambers were measured using 32 RTD sensors before and after the design changes. The temperature distributions were in the ranges of 87.1 to $91.5^{\circ}C$ ($90{\pm}2.9^{\circ}C$) and 89.5 to $90.8^{\circ}C$ ($90{\pm}0.8^{\circ}C$) before and after the design changes, respectively. The above temperature distribution after design changes was maintained for longer than 15 minutes, which satisfied the target temperature range of $90{\pm}1^{\circ}C$ for longer than 10 minutes.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.418-421
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• 2002

Fundamental study on quasi-monochromatic parallel radiography using a polycapillary plate and a plane-focus x-ray tube is described. The x-ray generator consists of a negative high-voltage power supply, a filament (hot cathode) power supply, and an x-ray tube. The negative high-voltage is applied to the cathode electrode, and the transmission type target (anode) is connected to the ground potential. The maximum voltage and current of the power supply were -100 kV (peak value) and 3.0 mA, respectively. In this experiment, the tube voltage was regulated from 20 to 25 kV, and the tube current was regulated by the filament temperature and ranged from 1.0 to 3.0 mA. The exposure time is controlled in order to obtain optimum film density, and the focal spot diameter was about 10 mm. The polycapillary plate is J5022-21 made by Hamamatsu Photonics Inc., and the outside and effective diameters are 87 and 77 mm, respectively. The thickness and the hole diameter of the polycapillary are 1.0 mm and 25 ${\mu}$m, respectively. The x-rays from the tube are formed into parallel beam by the polycapillary, and the radiogram is taken using an industrial x-ray film of Fuji IX 100 without using a screen. In the measurement of image resolution, we employed three brass spacers of 2, 30, and 60 mm in height. By the test chart, the resolution fell according to increases in the spacer height without using a polycapillary. In contrast, the resolution slightly fell with corresponding increases in the height by the polycapillary. In angiography, fine blood vessels of about 100 ${\mu}$m are clearly visible.

• The Journal of the Acoustical Society of Korea
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• v.34 no.5
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• pp.360-370
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• 2015

In case that an infinite length waveguide structure is connected with a finite length structure, it is required to combine a wave approach for the waveguide structure and a modal approach for the finite length structure to investigate the dynamic response of the connected target structure. In this study, the wavenumber finite element (WFE) analysis is adopted for the infinite length waveguide substructure and a finite element (FE) method is applied for the finite length substructure and then their results are coupled in terms of the impedance or mobility at the connected points between the substructures. As a structural model, an infinite length cylindrical shell with a rectangular plate inside is regarded. These two substructures are connected at the four corner points of the plate, rigidly or resiliently. From this investigation, it was confirmed that the wave approach (WFE method) and modal approach (FE method) can be combined by the impedance coupling.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.47-58
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• 2012

Dynamic behaviors of a corrugated steel plate tunnel lining system are examined under wind loads due to passing vehicles. Applied wind loads are simulated by applying the time functions as a vehicle moves through the tunnel. Wind loads are described by the pressure and suction as a vehicle arrives and leaves target positions in the tunnel. The tunnel lining is modeled using the simplified shell elements that retain the characteristics of the corrugated shapes. The displacements of the tunnel lining are evaluated under various conditions regarding wind velocity and the passing vehicles. The responses are found to increase as the vehicle velocity and wind velocity increase. A maximum displacement of 25mm occurs when two vehicles are crossing at the speed of 120km/h. A row of vehicles running consecutively minimally affects the dynamic responses with less than 2.5% of the dynamic responses enlarged and attributed to one running vehicle. It should be noted that the dynamic responses of the tunnel lining should be considered when there is no shotcrete applied.

• Tribology and Lubricants
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• v.36 no.4
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• pp.199-206
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• 2020

CoCr-based alloys have been developed as wear-resistant materials owing to their excellent mechanical properties and strong wear resistance. The purpose of this study is to experimentally assess the frictional and wear characteristics of CoCr-based alloys slid against two different counter materials subjected to various normal forces to determine the expansion applicability of CoCr-based alloys. CoCrMo and CoCr alloys were selected as the target materials and NiCr and NiCrB alloys as counter materials. Experimental tests were performed using a pin-on-reciprocating plate tribo-tester under dry lubrication. Before performing the tests, the surface of the specimens was observed through confocal microscopy and the hardness was measured using a micro-Vickers hardness tester. The wear volume of the plate was calculated at the end of the tests using confocal microscope data, and the wear rate was quantitatively obtained based on Archard's wear law. From the results, the wear rates of the CoCrMo specimens that slid against NiCr and NiCrB are 7.69 × 10^-6 ㎣/Nm and 5.26 × 10^-6 ㎣/Nm, respectively. The wear rates of the CoCr specimens that slid against NiCr and NiCrB were higher than those of the CoCrMo specimens by factors of approximately 4 and 8, respectively. The CoCrMo specimens further exhibited lower friction characteristics than the CoCr specimens. The findings of this study will be useful for expanded applications of CoCr-based alloys as wear-resistant materials for various mechanical parts.