• Journal of Advanced Marine Engineering and Technology
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• 제19권2호
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• pp.47-55
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• 1995

When the low heavy oil is using as fuel oil to the diesel engine, some problems such as corrosion resistance, wear resistance and heat resistance are happened in diesel engine's internal material, especially the adhesive wear of piston ring groove was occurred as a important problem. Therefore to prevent adhesive wear of its groove, the surface of its groove used to be electroplated with Chrominum and for its Chromium electroplating, Fe anode is being used until nowadays because of its Special shape. However in case of using Fe anode, there were some problems such as deterioation of solution, property of Chromium film, and condition of coation. In this paper Pb anode electroplated withPb to the steel plate was investigated for its Chromium electroplating for Pb's high corrosion resistance in acid solution, and Pb anode is not dissolved compared with Fe anode and deterioration degree of solution in case of Pb anode is smaller than that of Fe anode and also property of Chromium film was better than that of Fe anode. Moreover it was known that the optimum cathodic current density for Pb electroplating to steel plate as insoluable anode for Chromium coating of piston ring groove is 30mA/$cm^2$ by experimental results obtained.

• 동아시아식생활학회지
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• 제6권3호
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• pp.325-333
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• 1996

Potato slices were dipped in calcium choreide ar chitosan solutions or and preheated in each of these solutions. In order to prevent the quality deterioration while they were refrigerated for 4 weeks at 5$^{\circ}C$ Changes in degree of browning and other quality factors were determined while they were refrigerated for 4 weeks at 5$^{\circ}C$ During refrigeration, L values were decreased and optical density (A420) were increased. But L values were increased and A420 were decreased by dipping or preheating. The contents of vitamin C were decreased. however, the loss of vitmin C were the lowest in calcium chloride treaed potato slices(CaPS). And there were no combined effects of dipping and preheating during refrigeration. However, protein content of CaPS increased but that of other treated potato slices were decreased compared to that of control. With respect to changes in other physicochemical qualit, pH increased in chitosan treated potato slices(ChPS) and loss of weight was the lowest in combined with preheating. From these results, it was considered that the shelf-life of potato slices could be increased by dipping or-and preheating.

• 동아시아식생활학회지
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• 제25권1호
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• pp.146-152
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• 2015

Seasoned laver is the highest consumed item among processed laver foods. However, it easily undergoes quality deterioration during processing and storage by lipid oxidation. The purpose of this study was to develop onion seasoned laver with strengthened functional properties through evaluation of storage characteristics. Proximate composition, color index, acid value, thiobarbituric acid (TBA) production, and sensory evaluation of seasoned laver with 0, 15 and 30% onion powder were analyzed during storage periods of 0, 12 and 24 weeks. The lightness, redness, and yellowness of 30% onion seasoned laver significantly increased according to storage period. The acid value and TBA production significantly increased in control laver without onion powder, with no significant difference in 30% onion seasoned laver according to storage period. Sensory preference of onion seasoned laver was better than that of control laver in terms of taste, texture, and overall acceptability. To sum up these results, seasoned laver with 30% onion powder showed superior color degree, acid value, TBA production and sensory preference in proportion to added amount.

• 펄프종이기술
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• 제38권3호
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• pp.61-65
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• 2006

The objective of this study was to find in what color Korean handmade paper(Hanji) is dyed when it is dyed with a pigment extracted from mugworts using different kinds of mordant, and how the paper is discolored and variety of strength under the condition of accelerated aging test. The results of this experiment are as follows. Among mugwort mordants, only ferrous sulfate mordant produced unique khaki color with a slightly lower degree of discoloration, so it is considered to be applicable in dyeing Korean paper. Bright yellow and light green colors were obtained using mugwort but their chroma was too low for actual use. With regard to water used, colors obtained using underground water had high chroma, but when distilled water was used paper was colored in useless light green. Mordant was found to lower the strength of Korean handmade paper, and the lowering of strength was even more serious under the condition of forced deterioration.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1086-1092
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• 2015

The off-line and on-line partial discharge (PD) in the stator winding of three high-voltage (HV) motors (1,400 HP, 6.6 kV) is measured and analyzed in this paper. The off-line PD is measured at high values between 24,300 ~ 36,100 pC after 18 years of motor operation. Spare replacement motors were not available for testing the degree of deterioration of the stator windings in standstill status. Therefore, on-line periodic analysis was conducted to monitor the trend of PD after installing a ceramic sensor (110 pF, 6.6 kV) in the terminal box for each phase of each motor. In the stator winding of the No.1 and No.2 HV motors, which showed high magnitudes of off-line PD and low magnitudes of on-line PD, defects are expected to appear in the neutral end of the winding. On the contrary, in the stator windings of the No.3 HV motor, which exhibits high off-line and on-line PD magnitude, defects are expected to appear in the terminal end of the winding where a voltage close to the phase voltage is applied.

• 치과방사선
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• 제24권2호
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• pp.413-423
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• 1994

The purpose of this study was to clarify the spatial relationship in presurgical examination and to aid surgical planning and postoperative evaluation of patients with facial bone injury. For this study, three-dimensional images of facial bone fracture were reconstructed by computed image analysis system and three-dimensional reconstructive program integrated in computed tomography. The obtained results were as follows: 1. Serial conventional computed tomograms were value in accurately depicting the facial bone injuries and three-dimensional reconstructive images demonstrated an overall look. 2. The degree of deterioration of spatial resolution was proportional to the thickness of the slice. 3. Facial bone fractures were the most distinctly demonstrated on inferoanterior views of three-dimensional reconstructive images. 4. Although three-dimensional reconstructive images made diagnosis of fracture lines, it was difficult to identify maxillary fractures. 5. The diagnosis of zygomatic fractures could be made equally well with computed image analysis system and three-dimensional reconstructive program integrated in computed tomography. 6. The diagnosis of mandibular fractures could be made equally well with computed image analysis system and three-dimensional reconstructive program integrated in computed tomography.

• 한국환경농학회지
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• 제27권4호
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• pp.314-320
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• 2008

During the summer season, more than half of the annual precipitation in Korea occurs during the summer season due to the geographical location in the Asian monsoon belt. So, this causes severe soil erosion from croplands, which is directly linked to the deterioration of crop/land productivity and surface water quality. Therefore, much attention has been given to develop accurate estimation tools of soil erosion. The aim of this study is to assess the performance of using the empirical Universal Soil Loss Equation (USLE) and the physical-based model of the Water Erosion Prediction Project (WEPP) to quantify eroded amount of soil from agricultural fields. Input data files, including climate, soil, slope, and cropping management, were modified to fit into Korean conditions. Chuncheon (forest) and Jeonju (level-plain) were selected as two Korean cities with different topographic characteristics for model analysis. The results of this current study indicated that better soil erosion prediction can be achieved using the WEPP model since it has better power to illustrate a higher degree of spatial variability than USLE in topography, precipitation, soils, and crop management practices. These present findings are expected to contribute to the development of the environmental assessment program as well as the conservation of the agricultural environment in Korea.

• Geomechanics and Engineering
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• 제20권2호
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• pp.113-120
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• 2020

Rock damage is the main cause of accidents in underground engineering. It is difficult to predict rock damage accurately by using only one parameter. In this study, a rock failure prediction model was established by using stress, energy, and damage. The prediction level was divided into three levels according to the ratio of the damage threshold stress to the peak stress. A classification predicting model was established, including the stress, energy, damage and AE impact rate using Bayesian method. Results show that the model is good practicability and effectiveness in predicting the degree of rock failure. On the basis of this, a multi-parameter classification predicting deterioration model of rock failure was established. The results provide a new idea for classifying and predicting rockburst.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.227-236
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• 2002

The purpose of this study makes a retrofit and rehabilitation practice trough the analysis and the improvement for the underlying problem of current retrofit and rehabilitation methods. Therefore, the deterioration process, the damage cause, the condition classification, the fatigue mechanism and the applied quantity of strengthening methods for RC deck slabs were analyzed. Artificial neural networks are efficient computing techniques that are widely used to solve complex problems in many fields. In this study, a back-propagation neural network model for estimating a management on existing reinforced concrete bridge decks from damage cause, damage type, and integrity assessment at the initial stage is need. The training and testing of the network were based on a database of 36. Four different network models were used to study the ability of the neural network to predict the desirable output of increasing degree of accuracy. The neural networks is trained by modifying the weights of the neurons in response to the errors between the actual output values and the target output value. Training was done iteratively until the average sum squared errors over all the training patterns were minimized. This generally occurred after about 5,000 cycles of training.

• 한국농공학회지
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• 제39권3호
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• pp.108-114
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• 1997

Concrete is said to have a high degree of extensibility when it is subjected to large deformations without cracking. The cracking behavior of concrete in the field may even be more complex. For example, in mass concrete compressive stresses are developed during the very early period when temperatures are rising, and the tensile stresses do not develop until at a later age when the temperature begins to decline. Actual cracking and failure depend on the combination of factors and indeed it is rarely that a single adverse factor is responsible for cracking of concrete. The importance of cracking and the minimum width at which a crack is considered significant depend on the conditions of exposure of the concrete. The ultrasonic pulse measurements can be used to detect the development of cracks in structures such as dams, and to check deterioration due to frost or chemical action. An estimate of the depth of a crack visible at the surface can be obtained by measuring the transit times across the crack for two different arrangements of the transducers placed on the surface. In this paper, the concrete cracks that artificially introduced crack width is 1 and 2mm, crack depth is 2, 4, 6, 8cm were measured by Tc-To Method In consequence, the measured depth was increased with increase of measuring distance from concrete crack. The most reliable results were shown when the introduced crack width was 1mm, and the measuring distance was 10cm from concrete crack.