• Journal of Korean Society of Water and Wastewater
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• v.34 no.4
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• pp.251-258
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• 2020

Sewer deterioration models are needed to forecast the remaining life expectancy of sewer networks by assessing their conditions. In this study, the serious defect (or condition state 3) occurrence probability, at which sewer rehabilitation program should be implemented, was evaluated using four probability distribution functions such as normal, lognormal, exponential, and Weibull distribution. A sample of 252 km of CCTV-inspected sewer pipe data in city Z was collected in the first place. Then the effective data (284 sewer sections of 8.15 km) with reliable information were extracted and classified into 3 groups considering the sub-catchment area, sewer material, and sewer pipe size. Anderson-Darling test was conducted to select the most fitted probability distribution of sewer defect occurrence as Weibull distribution. The shape parameters (β) and scale parameters (η) of Weibull distribution were estimated from the data set of 3 classified groups, including standard errors, 95% confidence intervals, and log-likelihood values. The plot of probability density function and cumulative distribution function were obtained using the estimated parameter values, which could be used to indicate the quantitative level of risk on occurrence of CS3. It was estimated that sewer data group 1, group 2, and group 3 has CS3 occurrence probability exceeding 50% at 13th-year, 11th-year, and 16th-year after the installation, respectively. For every data groups, the time exceeding the CS3 occurrence probability of 90% was also predicted to be 27th- to 30th-year after the installation.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.2 no.3
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• pp.13-24
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• 2004

The purpose of this study is to reveal the effect of electrical stimulation of body composition in obese person. Subjects were 30s to 40s aged healthy workers(2004. 3. 8~4. 17) in the S general Hospital in Suwon and they were brought to manage obesity. Subjects were divided into control group(Female<0.85, Male<0.90) and study group(Female>0.85, Male>0.90) by WHR(waist-hip ratio) that is measured by Automatic body composition analyzer(InBody 3.0). And we divided the study group with randomized methods into group A(n=8) and group B(n=8). Then we compared and analyzed the change of muscle mass, body fat, abdominal girth, WHR, BMI(body mass index) after application of electrical stimulation, three times a week, for 30 minutes in each session with 50 Hz of pulse frequency, $20\;{\mu}s$ or $250\;{\mu}s$ of pulse duration. There was statistically meaningful decrement of body fat(p<0.05) and abdominal girth(p<0.05) but not of body weight, muscle mass, WHR and BMI in the control group after application of electrical stimulation with 50 Hz, $20\;{\mu}s$. There were meaningful change of abdominal girth(p<0.05), WHR(p<0.05) and BMI(p<0.05), but not of body weight, muscle mass and body fat after application of electrical stimulation with 50 Hz, $20\;{\mu}s$ in group A. We applied electrical stimulation with 50 Hz, $250\;{\mu}s$ in group B, then there were meaningful change of body weight(p<0.05), body fat(p<0.01), abdominal girth(p<0.01), WHR(p<0.05) and BMI(p<0.01) but not of muscle mass only. Consequently, the pulse duration is the main parameter of electrical stimulation that affect the body composition of obese person in this study and if we combined the diet control to reduce blood components we could have better result. So it would be more effective to manage localized obesity(in abdomen, thigh, upper arm, etc.) if you apply electrical stimulation considering the pulse duration.

• Archives of Craniofacial Surgery
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• v.19 no.1
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• pp.41-47
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• 2018

Background: The number of surgical risks recalled by a patient after surgery can be used as a parameter for assessing how well the patient has understood the informed consent process. No study has investigated the usefulness of a self-developed mobile application in the traditional informed consent process in patients with a nasal bone fracture. This study aimed to investigate whether delivery of information, such as surgical risks, through a mobile application is more effective than delivery of information through only verbal means and a paper. Methods: This prospective, randomized study included 60 patients with a nasal bone fracture. The experimental group (n=30) received preoperative explanation with the traditional informed consent process in addition to a mobile application, while the control group (n=30) received preoperative explanation with only the traditional informed consent process. Four weeks after surgery, the number of recalled surgical risks was compared for analysis. The following six surgical risks were explained: pain, bleeding, nasal deformity, numbness, nasal obstruction, and nasal cartilage necrosis. Results: The mean number of recalled surgical risks among all patients was $1.58{\pm}0.56$. The most frequently recalled surgical risk was nasal deformity in both groups. The mean number of recalled surgical risks was $1.72{\pm}0.52$ in the experimental group and $1.49{\pm}0.57$ in the control group. There was a significant association between mobile application use and the mean number of recalled surgical risks (p=0.047). Age, sex, and the level of education were not significantly associated with the mean number of recalled surgical risks. Conclusion: This study found that a mobile application could contribute to the efficient delivery of information during the informed consent process. With further improvement, it could be used in other plastic surgeries and other surgeries, and such an application can potentially be used for explaining risks as well as delivering other types of information.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.1
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• pp.37-46
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• 2003

The transient responses on arbitrarily interconnected digital transmission lines are analyzed by an efficient node discretization technique. Since the proposed node discretization technique offers an efficient means to discretize transmission lines, the transient waveform at any position on the arbitrarily interconnected lines is easily predicted. Dispersive microstrip multiconductor transmission lines arbitrarily connected are analized for generality. The derivation of frequency-dependent equivalent circuit elements of coupled transmission lines have been carried out by the spectral domain approach(SDA). The effects of variations of excited pulse width on the crosstalks of the high-speed microstrip coupled-lines are also investigated. It has been well known that the crosstalk spike level is monotonously increased when the coupling length and effective permittivity of substrate are increased. In this paper, it is found that the variations of crosstalk level are not further monotonous as shortening the exciting pulse width toward several picosecond. The results are verified by the generalized S-parameter technique.

• Journal of Radiation Protection and Research
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• v.25 no.4
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• pp.217-221
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• 2000

Radiotheraphy may be considered as one of the most effective treatments for digestive tumors. This procedure has major side effects, especially in fast growing tissues like intestinal mucosa. For this reason, the morphological changes in mouse jejunal villi after whole body ${\gamma}-irradiation$ were analysed. Four week old ICR male mice were irradiatied with 6.5Gy or 12Gy of whole body ${\gamma}-irradiation$ and were sacrificed 3 days later. Jejunum among intestine were taken for morphology. Samples were carried out dehydration process and sliced sample covered with paraffin was hold on the slide and then light microscopy was observed by Hematoxylin & Eosin staining. villi at both irradiated doses were showed that the length of villi were shortened and thickened and that lumen were expanded in comparison with non-irradiated group. Since willi have an important role in digestion and very sensitive to radiation from this test, it has a role of test parameter for finding radioprotectors as well as evaluating the biological effect by radiaton.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.460-466
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• 2018

With the development of information technology, the scale of computer software system is constantly expanding. Reliability and cost of software development have a great impact on software quality. In this study, based on the software failure interval time data, a comparative analysis was performed on the characteristics of the software development cost model based on the lifetime distribution following the Type-2 Gumbel and Erlang distribution in the NHPP model. As a result, the trends of the cost curves for the Go-Okumoto model and the proposed Erlang model and the Type-2 Gumble model both decreased in the initial stage and gradually increased in the latter half of the failure time. Also, Comparing the Erlang model with the Type-2 Gumble model, we found that the Erlang model is faster and more cost-effective at launch. Through this study, Software operators should remove possible defects from the testing phase rather than the operational phase to reduce defects after the software release date, it is expected to be able to study the prior information needed to understand the characteristic of software development cost.

• Computers and Concrete
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• v.14 no.1
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• pp.73-90
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• 2014

The traditional destructive tests in damage detection require high cost, long consuming time, repairing of damaged members, etc. In addition to these, powerful equipments with advanced technology have motivated development of global vibration based damage detection methods. These methods base on observation of the changes in the structural dynamic properties and updating finite element models. The existence, location, severity and effect on the structural behavior of the damages can be identified by using these methods. The main idea in these methods is to minimize the differences between analytical and experimental natural frequencies. In this study, an application of damage detection using model updating method was presented on a one storey reinforced concrete (RC) building model. The model was designed to be 1/2 scale of a real building. The measurements on the model were performed by using ten uni-axial seismic accelerometers which were placed to the floor level. The presented damage identification procedure mainly consists of five steps: initial finite element modeling, testing of the undamaged model, finite element model calibration, testing of the damaged model, and damage detection with model updating. The elasticity modulus was selected as variable parameter for model calibration, while the inertia moment of section was selected for model updating. The first three modes were taken into consideration. The possible damaged members were estimated by considering the change ratio in the inertia moment. It was concluded that the finite element model calibration was required for structures to later evaluations such as damage, fatigue, etc. The presented model updating based procedure was very effective and useful for RC structures in the damage identification.

• Earthquakes and Structures
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• v.19 no.5
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• pp.395-409
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• 2020

With verifications through many relevant researches in the past few decades, adopting the equivalent lateral force procedure for designing seismically isolated structures as a preliminary or even final design approach has become considerably mature and publicly acceptable, especially for seismic isolation systems that mechanically exhibit bilinear hysteretic behavior. During the design procedure, in addition to a given seismic demand, structural designers still need to previously determine three parameters, such as mechanical properties of seismic isolation systems or design parameters and performance indices of seismically isolated structures. However, an arbitrary or improper selection of given parameters might cause diverse or even unacceptable design results, thus troubling structural designers very much. In this study, first, based on the criterion that at least either two design parameters or two performance indices of seismically isolated structures are decided previously, the rationality and applicability of design results obtained from different conditions are examined. Moreover, to consider variations of design parameters of seismically isolated structures attributed to uncertainties of mechanical properties of seismic isolation systems, one of the conditions is adopted to perform bounding analysis for seismic isolation design. The analysis results indicate that with a reasonable equivalent damping ratio designed, considering a specific variation for two design parameters (the effective stiffness and equivalent damping ratio) could present more conservative bounding design results (in terms of isolation displacement and acceleration transmissibility) than considering the same variation but for two mechanical properties (the characteristic strength and post-yield stiffness).

• Wind and Structures
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• v.25 no.2
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• pp.131-156
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• 2017

This paper deals with the dynamic stability of embedded functionally graded (FG)-carbon nanotubes (CNTs)-reinforced micro cylindrical shells. The structure is subjected to harmonic non-uniform temperature distribution and 2D magnetic field. The CNT reinforcement is either uniformly distributed or FG along the thickness direction where the effective properties of nano-composite structure are estimated through Mixture low. The viscoelastic properties of structure are captured based on the Kelvin-Voigt theory. The surrounding viscoelastic medium is considered nonhomogeneous with the spring, orthotropic shear and damper constants. The material properties of cylindrical shell and the viscoelastic medium constants are assumed temperature-dependent. The first order shear deformation theory (FSDT) or Mindlin theory in conjunction with Hamilton's principle is utilized for deriving the motion equations where the size effects are considered based on Eringen's nonlocal theory. Based on differential quadrature (DQ) and Bolotin methods, the dynamic instability region (DIR) of structure is obtained for different boundary conditions. The effects of different parameters such as volume percent and distribution type of CNTs, mode number, viscoelastic medium type, temperature, boundary conditions, magnetic field, nonlocal parameter and structural damping constant are shown on the DIR of system. Numerical results indicate that the FGX distribution of CNTs is better than other considered cases. In addition, considering structural damping of system reduces the resonance frequency.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.5
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• pp.335-342
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• 2016

When dynamics changes occurred in an existing Bayesian Network (BN), the related parameters embedding on the BN have to be updated to new parameters adapting to changed patterns. In this case, these parameters have to be updated with the consideration of the causalities in the BN. This research suggests a framework for updating parameters dynamically using Expectation Maximization (EM) algorithm and Harmony Search (HS) algorithm among several Meta-Heuristics techniques. While EM is an effective algorithm for estimating hidden parameters, it has a limitation that the generated solution converges a local optimum in usual. In order to overcome the limitation, this paper applies HS for tracking the global optimum values of Maximum Likelihood Estimators (MLE) of parameters. The proposed method suggests a learning and propagation framework of BN with dynamic changes for overcoming disadvantages of EM algorithm and converging a global optimum value of MLE of parameters.