• Journal of Sensor Science and Technology
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• v.25 no.4
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• pp.264-270
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• 2016

Self-powered neutron detector (SPND) is a sensor to monitor a neutron flux proportional to a reactor power of the nuclear power plants. Since an SPND is usually installed in the reactor core and does not require additional outside power, it generates electrons itself from interaction between neutrons and a neutron-sensitive material called an emitter, such as rhodium and vanadium. This paper presents the simulations of the depletion sensitivity evaluations based on MCNP models of rhodium and vanadium SPNDs and light water reactor fuel assembly. The evaluations include the detail geometries of the detectors and fuel assembly, and the modeling of rhodium and vanadium emitter depletion using MCNP and ORIGEN-S codes, and the realistic energy spectrum of beta rays using BETA-S code. The results of the simulations show that the lifetime of an SPND can be prolonged by using vanadium SPND than rhodium SPND. Also, the methods presented here can be used to analyze a life-time of those SPNDs using various emitter materials.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2061-2078
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• 2006

The main purpose of this paper is to establish the high temperature structural integrity evaluating procedures for the next generation reactors, which are to be operated at over 500$^{\circ}C$ and for 60 years. To do this, comparison studies of the high temperature structural design codes and assessment procedures such as the ASME-NH (USA), RCC-MR (France), DDS (Japan), and R5 (UK) are carried out in view of the accumulated inelastic strain and the creep-fatigue damage evaluations. Also the application procedures of the ASME-NH rules with the actual thermal and structural analysis results are described in detail. To overcome the complexity and the engineering costs arising from a real application of the ASME-NH rules by hand, all the procedures established in this study such as the time-dependent primary stress limits, total accumulated creep ratcheting strain limits, and the creep-fatigue damage limits are computerized and implemented into the SIE ASME-NH program. Using this program, the selected high temperature structures subjected to two cycle types are evaluated and the parametric studies for the effects of the time step size, primary load, number of cycles, normal temperature for the creep damage evaluations and the effects of the load history on the creep ratcheting strain calculations are investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.29-38
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• 2005

The track pull-in behavior analysis in an optical disk drive (ODD) using plane phase and the evaluations for effecting parameters of it are discussed. Track pull-in, track capture procedure to do track following control, is a key factor to increase data transfer rate. First, the relative velocity between the beam spot of an optical pick-up and the target track of an optical disk is analyzed during the track pull-in procedure. In this process, it is showed that the track error signal has nonlinear characteristics which are depending on the time. Second, Runge-Kutta method to solve the nonlinear equation is applied to find the track pull-in behavior, and some optimal parameters to get stable and fast pull-in condition are obtained. Then, the phase plane analysis for track pull-in procedure is presented. Finally, some comments for the simulated results are discussed briefly.

• Journal of Chest Surgery
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• v.15 no.2
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• pp.194-203
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• 1982

In this investigation we undertook to evaluate the utility of radionuclide cardiac angiography in the detection of cardiac shunts before and after surgical correction. Time-activity curves of ventricles and lungs were evaluated after bolus intravenous injection of 99mTc-human serum albumin in 512 preoperative patients and 551 post-operative patients. Omitting 31 cases of technical failure due to poor bolus, we detected shunts in 459 cases of 481 preoperative evaluations, so the detectability was 95.4%. The cases which couldn`t be detected by this method had small amount of shunt. Also the degree of shunt detected by radioisotope methods were well correlated with oxymetry method. [r=0.89, p<0.01 ] In postoperative evaluations, 18 out of 411 patients with left to right shunt and 10 out of 140 right to left shunt were found to have remnant shunts with radionuclide cardiac angiography. Of the 28 cases with failed operation, 2 were confirmed in reoperation, 2 by cardiac catheterization, 2 by two -dimensional echocardiography. All except one .f these patients had membranous ventricular septal defects and those with left to right shunts had moderate to severe pulmonary hypertension and shunt amount. Also those had larger septal defects than control group. We consider that radionuclide cardiac angiography is a simple and noninvasive method which can show the preoperative diagnosis and postoperative follow up of cardiac shunts.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.192-201
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• 2011

The optimal evaluation algorithms for voltage regulation in the case where new dispersed sources are operated in distribution systems are studied. Handling the interconnection issues for proper voltage managements are often difficult and complicated because professional skills and enormous amounts of data during evaluations are needed. Typical evaluation algorithms mainly depend on human ability and quality of data acquired, which inevitably cause the different results for the same issue. Thus, unfair and subjective evaluations are unavoidable. In order to overcome these problems, we propose reasonable and general algorithms based on the standard model system and proper criterion, which offers fair and objective evaluation in any case. The proposed algorithms are divided into two main themes. One is an optimal algorithm for the voltage control of multiple voltage regulators in order to deliver suitable voltage to as many customers as possible, and the other is a proper evaluation algorithm for the voltage management at normal and emergency conditions. Results from a case study show that proposed methods can be a practical tool for the voltage management in distribution systems including dispersed sources.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1924-1934
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• 2011

This paper is concerned with the robustness evaluations of the guidance controller for a bimodal tram which is being developed by the Korea Railroad Research Institute (KRRI). The bimodal tram is an all-wheel steered multiple-articulated vehicle as a new kind of transportation vehicle. This vehicle has to be equipped with an automatic guidance system. In [1], such a controller has been recently proposed. However, since the performance is affected by weight change of the vehicle due to number of the passenger, model parameter uncertainties depending on the state of friction and the elasticity of the tire, and a typhoon, the controller designed must be examined with these conditions. As expected, because the vehicle dynamics is highly nonlinear, for the sake of investigating the robustness of the controller we compose two simulation ways based on the vehicle models which are implemented by the ADAMS and the MATLAB/LabVIEW toolboxes. Different uncertainties and a typhoon disturbance have been considered for the simulation conditions. Simulation results are shown.

• The Korean Journal of Health Service Management
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• v.6 no.1
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• pp.219-229
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• 2012

The purpose of this study is to introduce the web database for healthy city Wonju that contains healthy city indicators and materials. It has provided diverse information to public officers who are working on healthy city projects and citizens for monitoring and evaluating the projects, effectively. The web database was made on 2006 and was updated on 2009. The new Web database system was designed for supporting that the staffs of healthy city can manage all data update by themselves. The new Web database encompasses more recent information about health city projects. After identifying users' needs and reasons for modifying the fields of data, we added new indicators to the Web database. Some redundant indicators were deleted based on users' requests. The Web database quality evaluations were performed by using 13 quality evaluations constructs. Through all 13 constructs, less than 20% of study subjects felt that it did not satisfy their needs or expectations. Well developed and verified contents of the Web database for healthy city are very essential and important. The database makes healthy city projects alive by managing and sharing healthy city related data and indicators effectively.

• Earthquakes and Structures
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• v.11 no.4
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• pp.701-721
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• 2016

Base isolation is a well-established passive strategy for seismic response control of buildings. In this paper, an efficient framework is proposed for reliability-based design optimization (RBDO) of isolated buildings subjected to uncertain earthquakes. The framework uses reduced function evaluations method, as an efficient tool for structural reliability analysis, and an efficient optimization algorithm for optimal structural design. The probability of failure is calculated considering excessive base displacement, superstructure inter-storey drifts, member stress ratios and absolute accelerations of floors of the isolated building as failure events. The behavior of rubber bearing isolators is modeled using nonlinear hysteretic model and the variability of future earthquakes is modeled by applying a probabilistic approach. The effects of pulse component of stochastic near-fault ground motions, fixity-factor of semi-rigid beam-to-column connections, values of isolator parameters, earthquake magnitude and epicentral distance on the performance and safety of semi-rigidly connected base-isolated steel framed buildings are studied. Suitable RBDO examples are solved to illustrate the results of investigations.

• Ocean Systems Engineering
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• v.1 no.4
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• pp.337-353
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• 2011

In the present study, an offshore platform having large partial porous cylindrical members, which are composed of permeable and impermeable cylinders, is suggested. In order to calculate the wave force on large partial porous cylindrical members, the fluid domain is divided into three regions: a single exterior region, N inner regions and N beneath regions, and the scattering wave in each fluid region is expressed by an Eigen-function expansion method. Applying Darcy's law to the porous boundary condition, the effect of porosity is simplified. Wave excitation forces and wave run up on the structures are presented for various wave conditions. For the idealized three-dimensional platform having large partial porous cylindrical members, the dynamic response evaluations of the platform due to wave forces are carried out through the modal analysis. In order to examine the effects of soil-structure interaction, the substructure method is also applied. The displacement and bending stress at the selective nodal points of the structure are computed using various input parameters, such as the shear-wave velocity of soil, the wave height and the wave period. Applying the Monte Carlo Simulation (MCS) method, the reliability evaluations at critical structure members, which contained uncertainties caused by dynamic forces and structural properties, are examined by the reliability index with the results obtained from MCS.

• Korean Journal of Human Ecology
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• v.18 no.5
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• pp.1063-1075
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• 2009

This study intends to provide foundational data for enhancing the welfare of customers purchasing digital products through analyzing the notes from written on-line reviews. The data used for the analysis are 6,342 on-line reviews for cell phones and digital cameras released from November, 2007 until April, 2008, which was posted on Naver Knowledge Shopping from November, 2007 until June, 2008. Through the on-line reviews, this article analyzed the evaluations on the digital products' hardware, software, design, service, price, and other criteria and the customers' emotional experience in the process of purchase, use, and possession. According to the results of the analysis, negative evaluation and emotional experience were originated from the company's information provision methods and purchase process. In addition, insufficient information searches in the process of online purchases, consumers' low right consciousness, and impolite on-line reviews were also problematic. Customers' evaluations and emotional experiences on digital products were conducted in a complex way. Based on that, this research makes suggestions in the company's marketing, customer education, and theoretical aspect.