• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.65-72
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• 2024

Green Hydrogen demonstration complex is under conduction in Jeju island which is rich in renewable energy resources and will produces green hydrogen using a water electrolysis systems. In order to check durability of long-term operation, AST(accelerated stress test) was applied and the power pattern based on Jeju Island's wind power was applied. After 800 hours of repeated application of low current and high current, the performance of the PEM water electrolysis cell was reduced by up to 10% and by about 5.5% in operating conditions. As the result of impedance analysis, it can be seen that the electrode polarization resistance greatly increased than ohmic polarization resistance. In addition, when the durability evaluation was conducted by applying the wind power pattern of Jeju Island, the performance of the PEM water electrolysis cell showed up to 1.6% and a decrease of less than 1% in operating conditions. As a result of the impedance, it can be seen that the change of ohmic resistance and electrode polarization resistance is small.

• Journal of Acupuncture Research
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• v.22 no.6
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• pp.51-60
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• 2005

Objectives : This study was designed to evaluate the effect of inbalance of autonomic nerve system on peripheral facial palsy patients in comparison of Heart Rate Variability results of healthy control group with that of peripheral facial palsy group. Methods : The peripheral facial palsy patiens who visited the Dongguk university Bundang oriental medicine hospital from April to June in 2005 were tested Heart Rate Variability items which are Mean Heart Rate(MHRT), Standard Deviation of all the Normal RR intervals (SDNN), Root Mean Square of Successive Differences Between The Normal Heart Beats(RMSSD), Total Power(TP), Low Frequency, High Frequency, ratio between the Low Frequency and High Frequency power(LF/HF ratio). The Heart Rate Variability test results of peripheral facial palsy group were compared with the HRV test results of healthy control group who didn't have nervous disease, musculoskeletal disease, heart problem and pain for the past 6 months. Results : 1. MHRT was not significantly different between peripheral facial palsy group and healthy control group(P=0.18). 2. SDNN was not significantly different between peripheral facial palsy group and healthy control group(P=0.41). 3. RMSSD was not significantly different between peripheral facial palsy group and healthy control group(P=0.93). 4. TP was not significantly different between peripheral facial palsy group and healthy control group(P=094). 5. LF and HF were not significantly different between peripheral facial palsy group and healthy control group((P=0.34, 0.30). 6. LF/HF ratio was significantly different between peripheral facial palsy group and healthy control group(P=0.04). Conclusion : LF/HF ratio is generally used as autonomic nerve system evaluation and there was significantly statistical difference between peripheral facial palsy group and healthy control group.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.1-12
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• 2006

An existing Steel pipe, Cast iron pipe and Concrete pipe is can not escaped from aging, specially Metal tube is causing many problems that the quality of water worse is concerned about many rust and mike efficient use of preservation of water. The use of Glassfiber Reinforced Plastic Pipe(GRP PIPE) should be one of the possible scheme to get over these problems. The GRP PIPE has an excellent resistance power and the life is lasting from 50 to 100 years roughly. It's to be useful as a result of high durability and a good construction work also it is a light weight therefore can be expected to short the time of construction and man power. In this research, to executed the small-scaled model test, in-situ model test using CLSM of in-situ soil and to evaluated the stress - strain of the pipe also try to estimated how useful is. From the model test in laboratory, the vertical and horizontal deformation of the GRP PIPE measured in six instance using 200mm and 300mm in diameters. The value of experimentation, theory, analysis got the same results of the test, but the vertical and horizontal deformation gauged in small and the earth pressure was almost zero using CLSM of in-situ soil..

• Journal of Energy Engineering
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• v.25 no.3
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• pp.18-26
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• 2016

Mineral oil is the most widely used for electrical transformer, though some factors should be considered such as their environmentally harmfulness when it spill and low flash point. To cover these disadvantages, vegetable oil has developed because of its high biodegradability and thermal stability. However, it is necessary that many studies should conduct to reveal the detailed impacts of long-term operation as transformer oil. In this paper, we applied the accelerated aging test which simulate the real transformer circumstances using insulation paper, coil, steel at $150^{\circ}C$, which is higher than normal operation, for 2 weeks. To figure out the oxidation characteristics between mineral oil and vegetable oil test major properties and components such as total acid number, dielectric breakdown and dissolved gas components during that period. As a result of these tests, we found that vegetable oil has higher electric insulation ability than mineral oil though poor total acid number by hydrophile property. Vegetable oil also kept its thermal stability under the given circumstances.

• Ecology and Resilient Infrastructure
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• v.6 no.2
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• pp.109-119
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• 2019

Eutrophication has occurred due to the inflow of various water pollutants in many Korean reservoirs with low depth, and algal blooms of surface layer and low oxygenation of deep layer have repeated every year. There are several existing technologies to alleviate the stratification of reservoirs, but it is difficult to apply them in field sites due to the necessity of electric power and low economic efficiency. In this study, a non-powered water circulation system using natural energy of wind and water flow has been developed, and two test-beds constructed in the reservoirs with different conditions and examined its field applicability. Through computational fluid dynamics (CFD) simulation, it has been shown that the water circulation system could induce the downward flow to mitigate the stratification between surface and deep layers, and its influence radius could reach about 30 m. As a result of long-term monitoring of the test-beds, various water quality improvement effects have been observed such as moderation of DO fluctuation by water circulation, reduction of DO supersaturation and prevention of excessive pH rising. In order to improve the applicability of the water circulation system, it is considered necessary to review countermeasures against flood and depth conditions of each reservoir.

• Journal of Korean Orthopaedic Sports Medicine
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• v.7 no.2
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• pp.95-121
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• 2008

Purpose: The goal is to identify the effectiveness of the IKDC subjective score in the clinical outcome study after reconstruction of the anterior cruciate ligament. Materials and Methods: Twenty-four patients after ACL reconstructions using twelve hamstring autografts and twelve Achilles allografts were evaluated. Lysholm knee score, IKDC subjective score, Knee Outcome Survey score and Tegner activity score were evaluated for the subjective outcome value. Static instability tests, Biodex dynamometer and one-legged hop for distance tests were done for the objective outcome value. Three functional performance tests (FPTs) including Carioca test, Shuttle run test and Co-contraction test were performed for deciding the final results. Each scale was compared with FPTs results and Pearson's correlation test was used to test the correlation between the parameters. Results: IKDC subjective score, single hop test, and quadriceps power in low velocity of Biodex dynamometer tests had a positive correlation with the total FPTs results. Conclusion: IKDC subjective score can be an effective test to evaluate the functional status as well as the subjective outcome after ACL reconstruction.

• Journal of IKEEE
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• v.18 no.1
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• pp.152-158
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• 2014

It is very important to supply the diesel fuel from fuel tank to combustion chamber in case of cold start procedure. the paraffin hydrocarbons are easily solidified at low fuel temperature and it can be blocking the fuel supply to the high pressure fuel pump. In order to reduce the fuel crystallization (Waxing), it have been used to develop not only cold flow additives but also the proper mounting design of fuel filter. Block heater in the fuel filter assembly have been also contained to improve the cold start and prevent blocking the fuel supply in Common Rail Direct Injection System. we can obtain the fuel pressure drop and fuel flow rate, power consumption of fuel heater to have the cold flow evaluation test with the saperated and composited fuel heater at the low ambient temperature, Due to evaluating cold flow performance of two block heater, we knew that composited package fuel heater was the excellent cold flow performance compared to separated type and obtained the parameters of cold flow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1734-1739
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• 2014

In this paper, microstrip low pass filter using transmission line with the modified DCRLH structure is designed and fabricated to be removed a spurious resonant mode, and a deep attenuation in stop band. The low pass filter is composed of shunt open-stub to get a deep attenuation and series short-stub to eliminate the spurious harmonics in stop band. In this way, the spurious harmonics occurring on the higher order frequency are suppressed and the filter performance is improved. Insertion loss and VSWR of the fabricated microstrip low pass filter in the passband from DC to 1.5 GHz is 1.26 dB and 1.65, and attenuation on the stopband from 1.84 GHz to 2.18 GHz is less than -100 dB. And also this filter has a good performance for 20 watt power test.

• Tribology and Lubricants
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• v.32 no.4
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• pp.113-118
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• 2016

As an economic, high quality, and highly reliable gear with low noise and low vibration is demanded, an overall finite element analysis regarding a gear is required. Also, an infrared thermography test, which is a quantitative testing technique, is demanded for safety and longer lifespan of gear products. In order to manufacture a gear product or to determine safety of a gear being used, it is necessary to precisely determine ingredients of a material constituting a gear and detect any internal defect. This study aims to realize a design that minimizes the spur gear displacement with respect to power during its rotation and ensures the spur gear control capacity by using a 3D model and the midasNFX program. This facilitates the assessment of the possibility of cracking by evaluating the stress intensity and focusing on the integrity of the spur gear. We prepare the specimen of the spur gear based on the possibility of cranking as per the result of the structural interpretation from an infrared ray thermal measuring technique. After cooling the spur gear, we perform experiments using thermography and halogen lamps and analyze the temperature data according to the results of the experiment. In the experiment which we use thermography after cooling, we find a rise in the temperature of the room. As a result, the defective part show temperatures lower than their surroundings while the normal parts have temperatures higher than the defective parts. Therefore, it possible to precisely identify defective part owing to its low temperature.

• Journal of the Korea Concrete Institute
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• v.13 no.3
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• pp.294-300
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• 2001

The effectiveness of bottom ash on the mechanical and physical properties of Controlled Low-Strength Material(CLSM) is investigated in this study, CLSM is defined by the ACI Committee 229 as a cementitious material that is in a flowable state at the time of placement and having a specified compressive strength of 83 kgf/$\textrm{cm}^2$ or less at the age of 28 days. This study was undertaken on the use of bottom ash as a fine aggregate in CLSM. Four different levels of bottom ash with fly ash contents, 25%, 50 %, 75%, 100%, are investigated. Laboratory test results conclude that inclusion of bottom ash increases the demand for mixing water in obtaining the required flow. However, the sand was reduced because it was adjusted to maintain a constant total volume. Miかe proportions were developed for producing CLSM at three 28-day strength levels: removal with tools (less than 7 kgf/$\textrm{cm}^2$), mechanical means (less than 20 kgf/$\textrm{cm}^2$), and power equipment (less than 83 kgf/cm\`). The physical and mechanical properties supports the concept that by-product bottom ash can be successfully used in CLSM.