• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.1-9
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• 2021

A60 class deck penetration piece is a fire-resistance apparatus installed on the deck compartment to protect lives and prevent flame diffusion in fire accidents. In case that the A60 piece is newly developed or its initial design is revised, it is important to verify the fire resistance performance using a fire test procedure (FTP) code. In this paper, transient heat transfer analysis was carried out to evaluate the fire resistance design compatibility of the newly devised A60 piece. The analysis results were verified via a fire test. The heat transfer characteristics were also investigated by comparing design specifications, such as diameter, internal configuration, and material type. The analysis was performed using ABAQUS/Implicit, and the fire test was performed according to the FTP code. The fire resistance performance of the A60 pieces satisfied the safety of life at sea convention regulation. The material type was the most important design specification for the A60 piece. Based on the maximum test temperature, the measured temperature of SUS316L material was 25% lower than that of S45C on average. The differences between thermal conductivity and specific heat of each material were 17% and 58%, respectively.

• Food Engineering Progress
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• v.13 no.4
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• pp.297-301
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• 2009

This study was performed to develop a prediction model of sugar content for strawberry. Near-infrared (NIR) spectroscopy has been prevailed for on-line and portable applications for non-invasive quality assessment of intact fruit. This work presents effects of illumination method and coating of reflection surface of light source on prediction result of sugar content. Effect of preprocessing methods was also examined. A low-cost commercially available VIS/NIR spectrometer was used for estimation of total soluble solids content (Brix). To predict sugar contents of strawberry, the best results were obtained with the spectrum data measured under intensive illuminations at three locations induced from the light source with fiber optic bundles. Gold coating of reflection surface of light source lamp gave favorable effect to prediction result. The best results in validation of PLSR model were $r_{SEP}$ = 0.891 and SEP = 0.443 Brix under OSC preprocessing and those of PCR were $r_{SEP}$ = 0.845, SEP $r_{SEP}$= 0.520 Brix, under no preprocessing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.541-549
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• 2018

This paper deals with the braking dynamic behavior of diesel electric locomotive pulling domestic cargo and passenger vehicles. Friction coefficient, pneumatic pressure, and running resistance affecting the braking system were tested. For the friction coefficient, the Dynamo test was performed with reference to UIC 541-4. The results are analyzed by multivariate regression and the relationship between braking force and ititial velocity is presented. The pneumatic pressure were classified into service braking and emergency braking. In order to reflect the characteristics of the brake valve and piping, the pressure rising over time was measured in the vehicle. In order to reflect the external force acting on the vehicle, we carried out the test of EN 14067-4 and presented the second order polynomial formula on a running resistance. The running resistance test results were compared with other countries. The dynamic behavior of a diesel electric locomotive running on a straight flat track based on vehicle resources, friction coefficient, braking pressure, and running resistance is simulated using the time integration presented in EN 14531-1. The simulation results were compared and verified with the vehicle braking test results. The results of this study can be used to analyze the dynamic braking behavior of a train. Also, it is expected that various parameters affecting braking in vehicle design can be analyzed and used as basic data for braking performance improvement.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.4
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• pp.221-228
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• 2019

Experimental investigation was performed to analyze the flow field characteristics and power generation performance for a shroud tidal power generation system. Electrical power output was compared with the rotational speed of the turbine blade and electric load connected to the generator for various flow velocity. As the electrical load decreased, the speed of the turbine increased rapidly and reached by about 2 times. The power output also increased remarkably with the decrease of load, and then decreased after maximum power point. In addition, the maximum power point appeared at high electrical loads as the experimental flow velocity increased. These results of the flow field characteristics and power generation performance analysis of the shroud tidal power generation system variation with the flow velocity conditions and electrical load are expected to be the basic data necessary for the development of efficient shroud tidal power generation system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.821-827
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• 2018

In devices used for re-forming osteoblasts to treat osteoporosis, a magnetic field is applied from the outside of the bone, and the minerals contained in the bone are aligned in a certain direction and undergo precessional motion. When a $90^{\circ}$ RF pulse is applied by using an RF coil, protons of minerals are brought to an excited state, and phosphorus activity promoting the deposition of osteoblasts in the bone is increased, thereby reshaping the bone. Miniaturizing the RF coil that generates a signal corresponding to the harmonic of the precessional motional frequency by means of the $90^{\circ}$ RF pulse can drastically reduce the overall size of the bone reshaping system. In this study, we propose a methodology for the miniaturization of the RF coil that can be used for osteoblast re-formation using a bone reshaping system. The capacitance of the designed RF coil is 25 pF, the inductance is approximately 100 nH, and the resonance frequency is 96 MHz. The radius of the end ring of the designed RF coil is 18 cm, and the total length of the leg is $2{\times}11.6cm$. The performance of the coil is verified through post-design measurement.

• Journal of Food Hygiene and Safety
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• v.34 no.4
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• pp.325-333
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• 2019

The present study was carried out to identify the distribution characteristics of heavy metals in ginseng and wood-cultivated ginseng reduction of dietary exposure. Samples of ginseng and wood-cultivated ginseng were collected from 14 and 5 regions across Korea, respectively. Lead (Pb), cadmium (Cd) and arsenic (Ar) were detected by ICP-MS after microwave digestion, whereas aluminum (Al) was determined using ICP. Cultivated ginseng peels were 16.2% of whole root, while the peels and fine roots amounted to 21.8% and 16.8% of whole wood-cultivated ginseng, respectively. Taking into account the weight and concentration of the heavy metals by root part, their distribution ratios were calculated and compared. The cultivated ginseng peels contained 40.3% Pb, 25.9% Cd, 47.6% As, and 89.9% Al. Meanwhile, heavy metals consisting of 27.2% Pb, 28.2% Cd, 48.3% As, and 56.8% Al were distributed in the peels of the wood-cultivated ginseng. There was no significant difference between the peels and fine roots of the wood-cultivated ginseng with respect to the distribution proportion of heavy metals, except for Al. These results indicate that the level of dietary exposure to heavy metals could be reduced by peeling ginseng and wood-cultivated ginseng prior to consumption.

• Clean Technology
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• v.25 no.3
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• pp.263-272
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• 2019

Air pollutants have a high impact on everyday life as well as on human health; therefore, new technologies such as low-emission vehicles and add-on systems for air pollutant reduction are needed for our society. However, the environmental benefits and costs of those technologies are not taken into account in existing economic feasibility assessments, which is a barrier that needs to be overcome for green technology to achieve wide dissemination and fast penetration in the market. Thus, this study develops a methodology to assess the economic feasibility of an air pollutant reduction technology by taking into account the social costs from air pollutants and carries out a case study to validate the methodology. Because the social unit costs for air pollutants have not been evaluated yet in South Korea, the methodology uses the social unit costs evaluated for the European Union that are then converted to those for South Korea based on the measuring criteria for vehicle emission gases, parity purchasing price, foreign currency exchange rate, and customer price index. The social unit costs for South Korea are used to assess economic feasibility. A case study was performed to assess the economic feasibility of a dual fuel system using diesel and compressed natural gas by taking into account social costs from air pollutants as well as economic costs. This study could contribute to assessing the true economic feasibility of green technology, projects, and policy related with air pollutant reduction.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.3
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• pp.132-142
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• 2019

Purpose: The purpose of this finite element analysis study is to introduce the novel Lock screw system and analyze its mechanical property to see if it can prevent abutment screw loosening. Materials and Methods: The Lock screw is a component tightened on the inside of the implant abutment which applies compressive force to the abutment screw head. To investigate the effect, modeling was done using CAD program and it was analyzed by finite element analysis under various load conditions. First, the preload was measured according to the tightening torque of the abutment screw then it was compared with the theoretical value to verify the analytical model. The validated analytical model was then divided into those with no external load and those with 178 N, and the tightening torque of the lock screw was changed to 10, 20, 30 Ncm respectively to examine the property of stress distribution on the implant components. Results: Using Lock screw under various loading conditions did not produce equivalent stresses beyond the yield strength of the implant components. In addition, the axial load was increased at the abutment-abutment screw interface. Conclusion: The use of Lock screw does not exert excessive stress on the implant components and may increase the frictional force between the abutment-abutment screw interface, thus it is considered to prevent loosening of the abutment screw.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.617-626
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• 2019

This study analyzes the optimal location of gas detectors through the gas dispersion in a cargo compressor room of a 174K LNG carrier equipped with high-pressure cargo handling equipment; in addition, we propose a reasonable method for determining the safety regulations specified in the new International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC). To conduct an LNG gas dispersion simulation in the cargo compressor room-equipped with an ME-GI engine-of a 174 K LNG carrier, the geometry of the room as well as the equipment and piping, are designed using the same 3D size at a 1-to-1 scale. Scenarios for a gas leak were examined under high pressure of 305 bar and low pressure of 1 bar. The pinhole sizes for high pressure are 4.5, 5.0, and 5.6mm, and for low pressure are 100 and 140 mm. The results demonstrate that the cargo compressor room will not pose a serious risk with respect to the flammable gas concentration as verified by a ventilation assessment for a 5.6 mm pinhole for a high-pressure leak under gas rupture conditions, and a low-pressure leak of 100 and 140 mm with different pinhole sizes. However, it was confirmed that the actual location of the gas detection sensors in a cargo compressor room, according to the new IGC code, should be moved to other points, and an analysis of the virtual monitor points through a computational fluid dynamics (CFD) simulation.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.149-154
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• 2018

This paper describes the fabrication and heat transfer property of 50 watts rated LED array module where multiple chips are mounted on chip-on-board type ceramic-metal hybrid substrate with high heat dissipation property for high power street and anti-explosive lighting system. The high heat transfer ceramic-metal hybrid substrate was fabricated by conformal coating of thick film glass-ceramic and silver pastes to form insulation and conductor layers, using thick film screen printing method on top of the high thermal conductivity aluminum alloy heat-spreading panel, then co-fired at $515^{\circ}C$. A comparative LED array module with the same configuration using epoxy resin based FR-4 PCB with thermalvia type was also fabricated, then the thermal properties were measured with multichannel temperature sensors and thermal resistance measuring system. As a result, the thermal resistance of the ceramic-metal hybrid substrate in the $4{\times}9$ type LEDs array module exhibited about one third to the value as that of FR-4 substrate, implying that at least triple performance of heat transfer property as that of FR-4 substrate was realized.