• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.767-773
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• 2017

Infrared stealth is an important technology for naval ships. This technology helps improve the anti-detection performance and survivability of naval ships. In general, the infrared signature of naval ships are categorized into internal and external heat source. External signature are generated by ship surface heating by solar flux as well as the complicated heat transfer process with the surrounding weather condition. Modern naval ships are equipped with seawater injection nozzles on the outside for nuclear, biological and, chemical, and these nozzles are used to control external signature. Wide nozzle placement intervals and insufficient injection pressure, however, have reduced seawater dispersion area. To address this problem, nozzle installation standards must be established. In this study, an actual-scale experimental system was implemented to provide the evidence for nozzle installation standards in order to reduce the infrared signature of naval ships. In addition, the environmental conditions of the experiment were set up through computational fluid dynamics considering the ocean climate data and naval ship management conditions of South Korea. The dispersion distance was measured using a high-resolution thermography system. The flow rate, pipe pressure, and dispersion distance were analyzed, and the evidence for the installation of seawater injection nozzles and operation performance standards was suggested.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.633-636
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• 2017

This thesis is about the evaluation method of field uniformity for radiated immunity test of vehicle component. Radiated immunity test is to find out whether a EUT has enough immunity or hold normal operation during applied electromagnetic interference. Field Uniformity(FU) measurement is essential for generate uniform field on DUT and Harness. But Standard of Radiated Immunity(RI) test for vehicle component based on ISO 11452-2 has not been specified a Field Uniformity(FU). So compared and analyzed with other standard which is defined by a specified a Field Uniformity. As a result, deviation occurs in the difference test condition and test method. In this thesis, proposal new measurement method of field uniformity that is considered test conditions of ISO 11452-2 and check the validity through actual test.

• Journal of Power System Engineering
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• v.6 no.1
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• pp.20-26
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• 2002

The purpose of this study is preventing the stick, scuffing, scratch between piston and cylinder in advance, and obtaining data for duration test in actual engine operation. The temperature gradient in cylinder bore according to coolant temperature were measured using $1.5{\ell}$ class diesel engine. 20 thermocouples were installed 2mm deep inside from cylinder wall near top ring of piston in cylinder block, at which points major thermal loads exist. It is suggested as proper measurement points for engine design by industrial engineers. Under full load and $70^{\circ}$, $80^{\circ}C$ and $90^{\circ}C$ coolant temperature conditions, the temperature in cylinder block and engine oil increased gradually according to the increase of coolant temperature, the siamese side temperature of top dead center is $142^{\circ}C$ in peripheral distribution, that is about $20^{\circ}C$ higher than that at thrust, anti-thrust, and rear side temperature, respectively. The maximum pressure of combustion gas in $70^{\circ}C$ coolant temperature is about 2 bar lower than those of $80^{\circ}C$ and $90^{\circ}C$ coolant temperature. The engine torque in $80^{\circ}C$, $90^{\circ}C$ coolant temperature condition is about 4.9Nm higher than that of $70^{\circ}C$ coolant temperature.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.50-55
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• 2015

Application of newly conceptualized Anti-Splash Devices designed for COT vent pipes were studied on a P/V valve located on the upper deck of an oil carrier vessel. Anti-Splash devices are used in the shipbuilding industry in order to avoid oil overflow and spray accidents caused by excess pressure and vacuum condition in the cargo oil tanks. These conditions are caused by the transverse and longitudinal sloshing forces that arise from ship motion during sea voyages. The main issue with existing Anti-Splash device model is flux at the outlet of the Anti-Splash Device, and so, new conceptual models for the Anti-Splash device were developed and compared to existing Anti-Splash device model using CFD analysis. Transient analysis was used to capture the flow and velocity of each model and a comparative analysis was performed between old and new-concept models. This data was used to determine the optimal design parameters in order to develop an optimized Anti-Splash Device. A Factory acceptance test was performed on the new-concept models in order to verify the performance and efficiency against their design requirements and other criterion. The final step performed was to apply the optimized Anti-Splash Device models for COT vent pipes to an actual vessel and verify performance through a seawater cargo operation during a sea voyage as per the ship owner's request. The patent for the aforementioned device was obtained by the Korean Intellectual property Office dated Dec. 18th,2014.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.32-39
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• 2019

Sensor pods mounted on the exterior of the aircraft used for tactical missions should have a fatigue life based on the expected load spectrum during operation. For mission equipment such as the sensor pod, the frequency fatigue life prediction method which applies the dynamic vibration environment condition is preferred due to the efficiency of the analysis. In this paper, a fatigue life prediction method in the frequency domain where stress due to static and dynamic loads is synthesized based on the actual flight load spectrum is proposed. After comparison with the existing analysis method, the fatigue life of the proposed analysis method was predicted conservatively. The proposed sensor pods satisfy the requirements of the fatigue life.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.443-448
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• 2023

Over the past five years, the number of patients with sleep disorders has increased by about 250,000 from 840,000 in 2017 to 1.09 million in 2021. In addition, sleep disorder is a factor that causes dementia risk factors, and furthermore, the population with sleep disorder is a very important policy issue in terms of stable health insurance financial management in the future in terms of national health management in the super-aging trend. Therefore, this study aims to establish an efficient treatment environment in medical institutions responsible for the current status of polysomnography and effective reimbursement policies for the recently increasing population with sleep disorders, and appropriate sleep management policies for future sleep disorders through correct implementation. We are trying to find out the actual condition and improvement plan through interviews with related organizations and experts.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.3
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• pp.229-238
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• 2010

In order to acquire a realistic forecast for the lifetime and post-closure period of the LILW (Low- and Intermediate-Level Radioactive Waste) repository and to establish the overall management plan associated gas issues. it is essential to carry out the long-term experimental research in a similar condition to actual disposal environment. Regarding this, as a part of the following-up actions on a construction and operation license for the first stage of the LILW repository at Gyeongju city, a large-scale in-situ experiment is being planned. For securing basic data on the experiment, the experimental researches related to gas generation previously performed in foreign countries are reviewed in detail. Consequently, it is judged that data on the gas generation experiment in Finland could be practically applied as the benchmark for our large-scale in-situ experiment because the same disposal concept as the Korean repository is adopted and the experiment is performed in a scale large enough to allow the use of regular waste packages.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.8
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• pp.706-711
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• 2015

The fighter aircraft uses several different loading configurations for air-to-surface and air-to-air combat missions. To maintain wings-level flight with an asymmetric weapon configuration, a pilot controls a roll trim system. However, it is difficult to apply an accurate roll trim input for wings-level flight in the actual flight under disturbance. The inaccurate roll trim input degrades the performance of the roll autopilot system. In this paper, to solve this problem, an integrator was additionally designed in the command part of the roll autopilot system. The initial transient response was improved by scheduling the limiter to restrict the roll attitude error. As a result of the evaluation of the simulation for the designed flight control law, the roll attitude following performance was found to be improved in the autopilot system operation under the inaccurate roll trim condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.137-143
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• 2010

Complete dryness inside the stator is a necessary and sufficient condition for the leak test. Microcracks caused by high cycle fatigue due to operation are generated in stator windings, and they are interrupted by water molecules during the leak test. For this reason, during leak test, the wrong value is indicated when there are no leaks in stator windings. Generator manufacturers presents unique dryness judgment criteria for the leak test, but there is no actual criterion that accurately indicates the dryness point for the leak test. The reason is because stator winding has a complex structure and the absence of effective dryness equipment in power plants. This paper proposes a dryness judgment criterion to evaluate if inside the stator winding is dried completely and presents experimental results.

• Composites Research
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• v.23 no.1
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• pp.1-7
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• 2010

In this paper, finite element analyses for estimating the behavior of fractured femur just after the operation were carried out by using ABAQUS 6.71. A stainless steel bone plate and composite bone plates with various stacking angles were considered to find out the effect of bone plate properties on bone fracture healing. In order to simulate the actual state, contact conditions between the plate and bone and fractured bones were imposed on the finite element models and the whole analysis was divided by two steps; screw fastening step and load bearing step. The stress and strain distributions at the fracture site for the cases of the stainless steel and composite bone plates were analyzed and compared with. From the analyses it was found that the composite bone plate had potential advantages for effective bone fractures healing relieving stress shielding effect.