• Smart Structures and Systems
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• v.3 no.3
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• pp.281-298
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• 2007

The load carrying capacity of a bridge needs to be properly assessed to operate the bridge safely and maintain it efficiently. For the evaluation of load carrying capacity considering the current state of a bridge, static and quasi-static loading tests with weight-controlled heavy trucks have been conventionally utilized. In these tests, the deflection (or strain) of the structural members loaded by the controlled vehicles are measured and analyzed. Using the measured data, deflection (or strain) correction factor and impact correction factor are calculated. These correction factors are used in the enhancement of the load carrying capacity of a bridge, reflecting the real state of a bridge. However, full or partial control of the traffic during the tests and difficulties during the installment of displacement transducers or strain gauges may cause not only inconvenience to the traffic but also the increase of the logistics cost and time. To overcome these difficulties, an alternative method is proposed using an excited response part of full measured ambient acceleration data by ordinary traffic on a bridge without traffic control. Based on the modal properties extracted from the ambient vibration data, the initial finite element (FE) model of a bridge can be updated to represent the current real state of a bridge. Using the updated FE model, the deflection of a bridge akin to the real value can be easily obtained without measuring the real deflection. Impact factors are obtained from pseudo-deflection, which is obtained by double-integration of the acceleration data with removal of the linear components on the acceleration data. For validation, a series of tests were carried out on a steel plategirder bridge of an expressway in Korea in four different seasons, and the evaluated load carrying capacities of the bridge by the proposed method are compared with the result obtained by the conventional load test method.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.772-779
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• 2019

The subsea pipeline has received considerable attention as a high-value-added industry linked to the energy and steel industries including natural resource development. The design and installation of the subsea pipeline require a variety of key technologies to carry out the project. In particular, a thorough pre-verification process through pre-commissioning is essential for the safe operation of the subsea pipeline. The hydrotesting stage in the pre-commissioning process of the subsea pipeline is known to be affected significantly by the ambient temperature change; however, there is a little study based on the theoretical and numerical approach. In this study, the method of predicting the internal temperature change using the transient heat transfer method for the stage of hydrotesting during the pre-commissioning process of the subsea pipeline and the prediction method of the pressure variation in the pipeline using it were proposed. The predicted results were compared with field test results and its effectiveness was verified. The proposed analysis procedure is expected to contribute to the productivity improvement of the subsea pipeline installation project by enabling the prediction of pressure variation through pipeline heat transfer simulation from the initial design stage of the subsea pipeline installation project.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.137-146
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• 2002

Purpose : This paper introduces an improved classification approach which adopts a deterministic relaxation method and an agglomerative clustering technique for the classification of MRI using neural network. The proposed approach can solve the problems of convergency to local optima and computational burden caused by a large number of input patterns when a neural network is used for image classification. Materials and methods : Application of Hopfield neural network has been solving various optimization problems. However, major problem of mapping an image classification problem into a neural network is that network is opt to converge to local optima and its convergency toward the global solution with a standard stochastic relaxation spends much time. Therefore, to avoid local solutions and to achieve fast convergency toward a global optimization, we adopt MFA to a Hopfield network during the classification. MFA replaces the stochastic nature of simulated annealing method with a set of deterministic update rules that act on the average value of the variable. By minimizing averages, it is possible to converge to an equilibrium state considerably faster than standard simulated annealing method. Moreover, the proposed agglomerative clustering algorithm which determines the underlying clusters of the image provides initial input values of Hopfield neural network. Results : The proposed approach which uses agglomerative clustering and deterministic relaxation approach resolves the problem of local optimization and achieves fast convergency toward a global optimization when a neural network is used for MRI classification. Conclusion : In this paper, we introduce a new paradigm to classify MRI using clustering analysis and deterministic relaxation for neural network to improve the classification results.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.4
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• pp.706-718
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• 1997

Ceramometal crowns are common restorations in fixed prosthodontics because of their casting accuracy, the high strength properties of the metal, and the cosmetic appearance of porcelain. However, deterioration of the initial fit of the metal coping has been observed after the porcelain firing cycle. The distortion due to repeated firing makes it difficult to fit crown margin and elicits microleakage. The major causes of distortion are the residual stress that accumulate during wax-up, casting, cold work and the induced stress caused by the mismatch of porcelain-metal thermal contraction. This study examined the marginal fit changes of metal copings in relation to repeated firing and the effects of heat treatment that reduce the distortion resulted from residual stress. The marginal changes of the copings that were treated with conventional method and those treated with heat before repeated firing, were evaluated. The metal die which represented preparations of a maxillary central incisor was fabricated, and 45 wax patterns were cast with nonprecious metal alloys. The heat treatment of each group was performed as follows. Group 1(control) : Casting - Devesting - Cold work - Firing Group 2 : Casting - Heat treatment - Devesting - Cold work - Firing Group 3 : Casting - Devesting - Cold work - Reinvesting - Heat treatment - Devesting - Firing The copings were fired 3 times. After each firing, the marginal fit changes were measured with inverted metallurgical microscope at the 4 reference points located at labial, lingual, and both proximal surface. Measurements were compared, and statistically analyzed. The results were as follows ; 1. In all groups, the highest value of marginal fit changes of the copings studied were found after the first firing cycle. 2. When the distortion of each experimental group at the first firing cycle were compared, group 1 exhibited the greatest changes($20-27{\mu}m$), followed by group 2($9-13{\mu}m$), and group 3($8-10{\mu}m$). 3. The copings treated with heat before devesting(group 2) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 4. The copings treated with heat after reinvesting(group 3) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 5. No siginificant differences in marginal fit changes were found between the copings treated with heat before devesting(group 2) and the copings treated with heat after reinvesting(group 3). (p>0.01)

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.9-18
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• 2017

Construction Management at Risk (CMAR) is a project delivery method that enables CM companies to deliver projects at a Guaranteed Maximum Price (GMP). General contractors can apply CMAR from the initial design phase right through the construction phase to reduce risks and improve project performance. One of the major advantages CMAR offers is that it permits a general contractor to provide a comprehensive suite of preconstruction services, including estimating, a constructability review, value engineering, drawings and a specification review, green building, and Building Information Modeling(BIM), among others. However, general contractors in South Korea currently provide only limited preconstruction services using CMAR because few CMAR projects have yet been implemented in Korea and their experience using the method is therefore limited. This benchmark study of how foreign general contractors utilize CMAR in their projects, particularly during the preconstruction process, its purpose, and the roles and responsibilities of each of the different participants in successful implementations thus provides invaluable information and will serve as a useful guide for Korean contractors seeking to incorporate CMAR preconstruction services in their projects and thus improve the competitiveness of their construction businesses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.87-95
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• 2020

As an experimental study on the corrosion behavior of steel materials to which ATMS method using EIS was applied in concrete, immersion of Ca(OH)₂ saturated aqueous solution and NaCl aqueous solution simulating the environment inside concrete The corrosion behavior was tested. The equivalent circuit was derived through the analysis of the Nyquist plot, and the interfacial resistance and the polarization resistance of the Ca(OH)₂ aqueous solution were compared, and Al ATMS was the best interfacial resistance and Zn ATMS was the best polarization resistance. After burying ATMS steel material of cement mortar, the initial immersion impedance measurement value was the highest in the Zn ATMS test body in the impedance measurement by the immersion time by immersing it in the NaCl aqueous solution. Al ATMS test piece has the highest impedance and is highly reliable. This is because Al, which has a high ionization tendency, is continuously oxidized in a strong alkaline environment to form a film and protect the steel from permeation of chlorine ions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.175-182
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• 2021

As road noise became an issue, low-noise pavement (LNP) has emerged. The noise difference from general asphalt pavement (GAP) is a measure to explain the noise reduction of LNP. On the other hand, even for GAP, noise varies with the performance years (PY) and pavement condition. This study evaluated the representative noise value (RNV) by the speed and PY of GAP. Sections of 49selected from the National Road Pavement Management System, and the noise was measured at speeds from 50km/h to 80km/h at every 10km/h using the Close Proximity Method (CPX). Because the noise immediately after construction differed from the other, it was treated separately, and some outliers were removed. The noise increased with increasing PY. In addition, the noise increase by speed showed a reliable trend at all noise levels. The RNV for each speed and PY was obtained through analyses of the PY and speed. The average noise difference between the initial construction and the six-year-paced pavement was approximately 6dB. When evaluating the noise reduction of LNP, it is necessary to use RNV rather than the noise of old pavement. The RNV of GAP is necessary for a relative comparison with LNP and studying the road noise characteristics for each GAP type.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.252-259
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• 2019

Jet engine modulation(JEM) signals are widely used in the field of target recognition along with high-range resolution profile and inverse synthetic aperture radar because they provide specific information of the jet engine. To obtain the number of blades of the jet engine, the chopping frequency proportional to the number of blades must be extracted. In the conventional chopping frequency extraction method, an initial threshold value is defined and a method of detecting the chopping peak is used. However, this detection method takes time depending on the signal due to repetitive detection. Thus, in this study, we proposed to extract the chopping frequency using MUltiple SIgnal Classification(MUSIC) algorithm. We applied the MUSIC algorithm to a given JEM signal to find the chopping frequency and determine the blade number candidates. We also applied the MUSIC algorithm to other chopping frequency extractions to determine the score of the candidate groups. Unlike the conventional detection algorithm, which requires repetitive frequency detection, MUSIC algorithm quickly detects the accurate chopping frequency and reduces the calculation time.

• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.290-300
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• 1998

Background: CYFRA 21-1 is a tumor marker which measures a fragment of cytokeratin 19 expressed by epithelial cells in bronchus. It is known that cytokeratin 19 is abundant in squamous epithelial cell cancer of the lung. However, if the incidence of elevated serum CYFRA 21-1 level in patients with benign lung diseases or pulmonary tuberculosis with severe parenchymal damage is high the specificity of CYFRA 21-1 could be decreased. The purpose of this study is to investigate the changes of serum CYFRA 21-1 according to the degree of parenchymal damage and the usefulness of CYFRA 21-1 for diagnosing possibly combined lung cancer in patients with pulmonary tuberculosis. Method: We studied the changes of serum CYFRA 21-1 according to the sputum AFB stain, radiologic manifestation and history of treatment in 81 patients with pulmonary tuberculosis, and 20 healthy persons, 25 patients with lung cancer, as a control group. CYFRA 21-1 concentration in serum was quantified by the immunoradiometry assay(Centocor$^{(R)}$). Result: The results were as follow; Serum CYFRA 21-1 level was significantly lower in patients with pulmonary tuberculosis($1.54{\pm}1.19ng/mL$, p<0.01) as compared to patients with lung cancer($12.25{\pm}15.97ng/mL$), and was slightly higher than the level in heathy persons($0.90{\pm}0.49ng/mL$) but there was no significant difference. Serum CYFRA 21-1 level was below the cut-off value of 3.3ng/mL in 95 percent of patients with pulmonary tuberculosis but it was above the cut-off value in 64 percent of patients with lung cancer. Serum CYFRA 21-1 level was significantly higher in the initial treatment group($1.91{\pm}1.55ng/mL$, p<0.05) as compared to the treatment. failure group ($0.92{\pm}0.30ng/mL$). According to the sputum AFB smear, serum CYFRA 21-1 level in patients with negative result was slightly higher than the level in patients with positive result but there was no significant difference. According to the radiologic manifestation, serum CYFRA 21-1 level was significantly higher in patients with infiltrative lesion ($2.15{\pm}1.63ng/mL$, p<0.01) as compared to patients with destructive lesion ($l.04{\pm}0.54ng/mL$). As the size of cavity or destructive lesion was larger, the level was significantly lower(p<0.05). Conclusion: As serum CYFRA 21-1 level was significantly higher in the initial treatment group and patients with infiltrative lesion, it suppose to be closely related with the degree of parenchymal damage of the lung of the pulmonary tuberculosis. However CYFRA 21-1 could be useful method for diagnosing lung cancer even in patients with pulmonary tuberculosis combined with lung cancer because of the fact that it was below the cutoff value of 3.3ng/mL in 95 percent of patients with pulmonary tuberculosis.

• Applied Biological Chemistry
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• v.4
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• pp.33-42
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• 1963

1. Two fermentation methods have been compared for the production of Takju (Korean native Sake). One method (S1) uses 'Nuruk' (Korean mold wheat) and the other method (S2) uses 'Nuruk' and mold rice. The chemical analysis of source material, also, have been made in order the check the quantitative changes during the fermentation. The results are summarized below: a. The rate of fermentation was slower for the S2 method than for the S1 method. However, the residual sugar in the S2 method was smaller and the amount of alcohol produced the same as with the S1 method. This was true in spite of the fact that the total initial sugar content for the S2 method was 10 percent below that of S1. b. With both the S1 and S2 methods, 80 percent of the total alcohol production was obtained with in 3 to 4 days. c. The pH value of the base material at the beginning of fermentation was markedly different between the two methods I.e.6.0 to 6.2 for S1 and 4.8 to 5.2 for S2. However, after one or two day the pH of both materials was about the same 4.0 to 4.2 and remained at this value unit the fermentation was complete. 2. Organic acids and Sugars in the source materials have been detected by the paper partition chromatography(p.p.c.) method and the followings are obtained. a. Important Organic acids are Fumalic, malic Succinic, Citric, Acetic aicds in polished rice and Fumalic, Succinic, Acetic, Citric, Malic and Oxalic acids 'Nuruk'. The same kinds of acids as in the rice are found in mold rice, However, amount of Citrice acid is markedly increased in mold rice. b. The important Sugar, Glucose, Fructose and Raffinose in polished rice, Gulcose, Fructo, se, Xylose and one which supposed to be Kojibjose in 'Nuruk'. Glucose and those supposed to be Isomaltose, Kojibiose and Sakebiose and found in rice mold, however, no Sucrose, which was exist in polished rice, was found. 3. The important Organic acids found in fermenting mash using the p.p.c. method were Lactic, Succinic and Acetic. Citric acid identified early in the fermentation, S2 method. remained throughout. However, with the S1 method Cirtic acid was detected only during the late stage of fermentation. Sugars not found in the original materials were two which supposed to be Isomaltotriose and Pentose. Maltose found at the beginning of the fermentation disappeared within one day, Isomaltose was detected throughout the period of fermentation. 4. The Somogyi method which was employed to determine the quantitative changes of sugars in the orginal meterial and mach, showed that polished rice containes in order and in largest amounts Sucrose, Glucose, Raffinose and Fructose. 'Nuruk' contained almost equal quantities of Glucose and Fructose. However, the Glucose content of the mold rice exceeded that originally in the polished rice by 25 or 30 times. Only a small quantity of free sugars was found in the mash at the end of the fermentation.