This study was performed to investigate the effect of two step austenitized treatment on the mechanical properties and fracture characteristic of the ductile cast iron and austempered ductile cast iron(ADI). The obtained results of this study were as follows. The matrix structures of specimens were changed differently by austenitizing heat treatment. Microstructure of austempered ductile cast iron obtained by two step austenitized treatment was bainitic ferrite and retained austenite. With two step austenitized treatment, vield strength, tensile strength and hardness decreased, while the elongation increased.

The flexural strength from 3-point bend test and fatigue properties were measured to evaluate mechanical properties of metal/ceramic interface of the multilayer ceramic package produced through tape casting. From the results, the specimens with three electrode layers showed the highest strength. The temperature distribution with time during thermal cycle and thermal stresses with the change of electrode's shape have been estimated by mathematical modelling. Specimen affected by thermal shock, produced microcracks by the difference of thermal expansion coefficient. The results of tensile test and fatigue test showed the rupture at pin. The fact that the pin brazed specimens were always fractured at the pin proved the good bonding condition between pin and electrode.

In the study, we have developed a straightening system for 304 micro wires that are normally used in the medical and semi-conductor fields. To apply heat to the micro wires, we introduced the direct wire heating method which generates the thermal energy by the electrical resistance of the wire itself. To avoid the deterioration of the wire surface by the environment, such as the oxidation or the hydration, the $N_2$ gas was filled in the glass pipe in which the straightening process was being performed. A precision tension meter was also attached to control the tension of the wire during the heating and straightening process. In order to control the straightening process, several experimental investigations with varying the tension, the feeding velocity and the temperature (current) was carried out. As a result of experiments, we obtained the optimal processing conditions satisfying the straightness requirement of the micro wires.

Seat is one of the most important part of an automobile for passenger's safety especially when an accident happens. A recliner is a part of the seat assembly, having the function of adjusting the back-plate angle of a seat. Recently, many kinds of vehicles have adopted the round recliner module rather than the conventional types of recliners because of its broad compatibility and structural simplicity. In this study a two-dimensional finite element strength analysis has been performed using a commercial code ABAQUS/Standard for the purpose of developing a new round recliner model. The loading condition for the analysis is the same as the FMVSS 301 regulation. The finite element result for the round recliner has been compared with that for the conventional type.

Fine blanking can be considered as a manufacturing process capable of producing sheet metal parts with completely smooth edges that may be hardly obtained by conventional shear-cutting procedures. This fact, together with the considerable economic advantages offered by this process, has been responsible for the rapid acceptance of fine blanking throughout the manufacturing industry all over the world, and the discovery of many new applications. This study was performed to investigate the effect of clearance and V-ring shape on the quality of sheared surface in a fine blanking process. The critical value needed to apply the normalized Cockcroft-Latham fracture criterion to the simulation of fine blanking is obtained by correlating the result of finite element analysis and that of experiment for the uniaxial tensile test. From finite element analysis of an axisymmetric fine blanking process, it has been found that punch load, die-roll depth, burnish zone size and shape of sheared surface are considerably influenced by clearance and V-ring shape.

A performance analysis for newly being considered electric rail car office has been made in this study. The major purpose is to examine a proposed design in terms of its capacity and the proposed number of travels (82-84) per day. For this study we first examined the overall system configuration with detailed operational processes of cleaning and inspection. We then developed a simulation model using ARENA and designed input data from 12 selected factors and their interaction effects. A simulation run for each treatment combination of $L_{16}(2^{15})$ orthogonal array was run and 20 batch means were obtained. Through careful analyses of the results obtained, we drew a diversity of suggestions including the best factor level combination. Our confirmation experiments at the optimal level combination further validate the possibility of 82 runs and the consistency in the results.

Industrial efforts for increased market sales have directed towards the development and implementation of on-line marketing systems under recent e-business environment. Internet-based shopping mall is one of the most popular system. A business process model for an intermediary type shopping mall using IDEF0 has been presented in this study. Specific efforts have been focused on defining and analyzing a diversity of business processes embedded in practical B2B and B2C mall system operations. We first briefly examined the considered system with IDEF0 design. We then defined fundamental business processes within shopping mall systems. Upon careful examination and analysis of them, a detailed business process model based on IDEF methodology has been designed. The results in this study may well form a conceptual framework for shopping mall development and operations.

Personal identification using fingerprints needs much calculational effort. Generally, there are various methods for fingerprint-based identification. In this paper, an identification method is proposed which is based on direction distribution of fingerprint ridges. An 8-directional Gabor filter bank is used for extracting the feature vector from the given fingerprint. Then, it is compared with those of registered fingerprints for matching. This method is simple and fast to implement because it uses the information of ridge directions only. An experiment on 532 fingerprints from NIST database and some other source shows its usefulness.

The purpose of this study is to analyze the vibration signal of the revolution machine using the STFT(Short Time Fourier Transform). It is common to analyze the frequency of signal through FFT algorithm with the fixed sampling rate. However, in this situation the order spectrum information useful rather than the general frequency information with the fixed sampling rate. In this paper, the resampling technique was used for getting the information of order spectrum. In resampling process, the arithmetic amount and MSE(Mean Square Error) for various kinds of the signal interpolation was compared and presented the propriety of the interpolation method while developing analysis equipment. Order tracking was implemented using signal interpolation method which it has selected. Then the analyzed results were obtained through simulation using the STFT technique.

The metal halide lamps are now widely used in the application and commercial lighting due to their attracting properties such as good color rendering and high efficiency. But, they have the serious problem of acoustic resonance for high frequency operation and they need the high voltage to ignite. So, they have not been applied to indoors. Over the past few years, a considerable number of studies have been conducted on the electronic ballast together with hot restarting and resonance phenomenon. But, very few attempts have been made with the adaptive ignition method according to the lamp state. In this paper, electronic ballast is proposed for metal halide lamps with an igniter for adaptive ignition. The proposed electronic ballast can generate different ignition voltages according to the arc tube state.

Generally, electronic appliances are used on the basis of normal power source supply. The power source inevitably includes the abnormal condition, such as, sudden voltage sagging, power interrupt, and induced noises. As the electronic appliances which include micro-controller-based circuits are being increased recently, the controller circuit sometimes malfunctions by the abnormal condition of the power source. This situation causes serious problems such as hitch of electric appliance, fire and medical instrument glitch, which produces serious situations. In this paper, development of power interrupt tester which is highly suitable for an endurance test device under abnormal power source to microprocessor-based circuits is proposed 89C2051 microcontroller is performed to make power interrupt signal, and software controls peripheral hardwares and built-in functions. Experimental results of this study will offer a good application to electronic appliance maker as a test device of hardware and software debugging use.

This paper describes the design of a 2-phase stepping motor driver using CPLD(Complex Programmable Logic Device). The driver IC such as L297(SGS-Thomson Microelectronics), which is mostly used has some difficulties in PWM control because of the switching noise of power MOSFETs. It causes current ripple and acoustic noise. To improve theses characteristics, we proposed a new current control method that the output PWM frequency is almost constant using a digital filter. Also we proposed constant current method for 1-2 phase(half step) excitation. The proposed method is implemented with CPLD(Xilinx, XC9572-PC44). Experimental results show the effectiveness of the proposed method.

This paper considers reinforcement learning control with the self-organizing map. Reinforcement learning uses the observable states of objective system and signals from interaction of the system and the environments as input data. For fast learning in neural network training, it is necessary to reduce learning data. In this paper, we use the self-organizing map to parition the observable states. Partitioning states reduces the number of learning data which is used for training neural networks. And neural dynamic programming design method is used for the controller. For evaluating the designed reinforcement learning controller, an inverted pendulum of the cart system is simulated. The designed controller is composed of serial connection of self-organizing map and two Multi-layer Feed-Forward Neural Networks.

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor in commutation period with PWM pattern. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF. Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage in commutation period with PWM pattern, the torque ripple can be reduced. The simulation and experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

BLDC Motor is one of the widely utilizable motors in servo system. The accurate calculation of the power loss for the IGBT and Inverse diode with Bipolar and Unipolar switching modes the driving modes is important for the design of drives for their heat treatment. If it were not for temperature-sensors in devices, it is difficult to get direct power loss, so. Power losses may be modeled by computer modeling to obtain the Calculation of the Power loss for Inverter in BLDC Motor with switching modes which is presented in this paper. The computer modeling is carried out by Matlab simulation. The power loss consists of conduction losses Conduction losses are the source of occurrence due to The IGBT and Inverse diode currents. Switching losses are the source of occurrence due to switching on/off in the devices, and gives the dominant influence to the loss. As a result, the unipolar I mode is best in reducing the heat losses.

In this paper, we proposed an optical balance using a Michelson Interferometer structure. The frequency of the interference signal is changed nonlinearly related with a weight to be measured, and this frequency change is processed by a processor to give a measured weight. Several measurements were performed and the good results were obtained with the fluctuation of about 1g.

In this paper, we studied Automated External Defibrillator and Electro- Cardiogram System. Proposed System, CU-EX1, is a PC-based AED/ECG system that manages the data acquired by Paramedic CU-ER1. The system controls the transfer of data from the Paramedic CU-ER1 and the storage of the data in a local host computer. Patient data could be entered as soon as the rescue data is stored in a local computer. The system also displays the data on a local computer and facilitates review of rescue events.

A room and pillar mining method has been adopting at the Jeungsun limestone mine. To check stability of pillar with multiple and irregular openings, the size, shape and spacing of rib pillar were first designed using some empirical suggestions. The Finite Difference Method(FDM)was used to analyze the pillar stability. Twelve different cases with the variation of K(horizontal/vertical stress)values, different height and different spacing of pillar were used in this study. Finally Mohr-Coulomb criterion was adopted to calculate the safety factors. Horizontal and vertical displacement, maximum and minimum principal stresses, range of plastic zone and safety factors were calculated at each case. As a result of analysis, the size of one block is 160m long, 70m wide, 40m high with 20m wide rib pillar and 20m square column pillar. The overall recovery at this case can be estimated about 40%.

Air voids in hardened concrete have an important influence on concrete durability such as resistance of freezing and thawing, permeability and surface scaling resistance. Linear traverse method and point count method in ASTM standard method have been widely used to estimate the air void system in hardened concrete. However, these methods are not used at present time, because they are is exhausted much time and effort. In previous study, air voids system of concrete was estimated by spacing factor. The purpose of this study organizes image analysis method by analyzing air contents, air voids distributions by diameters, air voids system as well as spacing factors after hardened concrete. The experimental variables institute of depth of specimen(top, middle, bottom), air contents(AE contents 0, 0.01, 0.03%).

Latex modification of concrete provides the material with higher flexural strength, as well as high bond strength and reduced water permeability. However, If the thermal expansion properties of overlay concrete (latex-modified concretes) are big different from that of substrate (ordinary portland cement concrete), these would cause a big interfacial stresses and result in premature failure. Therefore, the purposes of this study were to investigate thermal expansion characteristics of latex-modified concrete with cement types. The result of thermal expansion showed the coefficient of thermal expansion of concretes increased with latex inclusion. The coefficient of thermal expansion of RSLMC was a little smaller than that of LMC, which might be due to the finer cement grain, compacter internal, and stiffer properties of concrete. However, the coefficients of LMC and RSLMC were quite similar to that of ordinary cement concrete. Thus, this would not cause an interfacial stresses and will enable to ensure long-term performance of concrete bridge deck overlays.

It is the purpose of this study to identify comprehensive fatigue characteristics of pavement concretes considering coarse aggregate types. The types of coarse aggregates considered are limestone, sandstone and granite, which are the most representative stones in Korea. The static strength tests were carried out to check the compressive strength, flexural strength at 7 and 28 days, and split tension strength at 56 day in order to minimize the various effect of strength during the test. The results are follows. The comprehensive fatigue models of pavement concretes were developed considering coarse aggregate types. The developed model showed a good relationship between aggregate types. The fatigue models with coarse aggregate types were shown, respectively. The combined fatigue models was also shown.

Each year, new technological advancements for repair-purpose are being introduced to overlay the old deterioration of RC bridge deck at highway by latex-modified concrete. The days may come when this old problem will be successfully resolved. While the experimental works and researches are very active at both laboratory and field, only a few theoretical studies were performed on interfacial problems, especially on stress distribution and concentration of RC beam overlayed by latex-modified concrete. The repaired and strengthened structures would induce a premature failure due to the stress concentration at the adhesive layer of different material before the design expected failure. This paper investigated and proposed an analytical model for predicting interfacial shear and normal stresses of RC beam repair-purpose overlayed by latex-modified concrete. This would be used for predicting interfacial stresses and preventing premature failure at interfaces. This study modified Smith-Teng method for applying to cementitious repairing material, which was based on a direct governing equation and linear-elastic approach for interfacial normal and shear stresses. The proposed theoretical model was verified using commercial FEA program, LUSAS, in terms of interfacial stresses predicted by the proposed model and calculated by LUSAS.

To evaluate seismic performance of reinforced concrete piers two procedures for capacity spectrum method are presented. The capacity spectrum procedures include the reduction factor-ductility-period($R_{\mu}-{\mu}-T$)relationship in order to construct the inelastic demand spectra from the elastic demand spectra. Application of the procedures are illustrated by example analysis. Maximum displacements estimated by the procedures are compared to those by inelastic time history analysis for several artificial earthquakes. The results show that the maximum displacements estimated by the procedures are, on overall, smaller than those by the inelastic time history analysis.

To evaluate inelastic seismic responses of multi-span bridge structures, the capacity spectrum method(CSM) incorporating the equivalent single-degree-of freedom(ESDOF) method is presented. Application of the CSM incorporating the ESDOF method is illustrated by example analysis for symmetric and asymmetric bridge structures. To investigate an accuracy of the CSM, the maximum displacements estimated by the CSM are compared to those by inelastic time history analysis for several artificial earthquakes. The results show that the CSM provided conservative estimates of the maximum displacements for the symmetric and asymmetric bridge structures, and the trend of conservative estimates of the asymmetric bridge structures was significantly larger than that of the symmetric bridge structure.

Static reliability models are introduced to analyze the armor stability of rubble-mound breakwaters. Contrasted to the deterministic model, reliability models can estimate the probability of failure directly and calculate the influence of each design variables quantitatively. Thus, it can be possible to design armor units of the rubble-mound breakwaters rationally. In this study FMA(First-order Mean-value Approach), FDA(First-order Design-value Approach) and AFDA(Approximate Full Distribution Approach) of Level II approach of static reliability methods are used to analyze the armor stability of rubble mound breakwaters. The limitations and applications of each approach are studied straight-forwardly.

A dynamic reliability model which can take into account the time history of loading sequences may be applied to the analyses of the hydraulic stability of armor units on rubble-mound breakwaters. All the parameters related to the stability of structures have been considered to be constants in the deterministic model until now. Thus, it is impossible to study the effects of some uncertainties of the related random variables on the stability of structures. In this paper, the dynamic reliability model can be developed by POT(Peak Over Threshold) method in order to take into account the time history of loading sequences and to investigate the temporal behaviors of stability of structure with its loading history. Finally, it is confirmed that the results of dynamic reliability model agree with straight- forwardly those of AFDA(Approximate Full Distribution Approach) of the static reliability model for the same input conditions. In addition, the temporal behaviors of probability of failure can be studied by the dynamic reliability model developed to analyze the hydraulic stability of armor units on rubble-mound breakwaters. Therefore, the present results may be useful for the management of repair and maintenance over the whole life cycle of structure.

This paper is results of experimental and nunerical works on the behavior of the cut-and-cover tunnel. Centrifuge model tests were performed to simulate the behavior of the cut-and-cover tunnels having cross sections of national road and subway tunnels. Model experiments were carried out with changing the cut slope and the slope of filling ground surface. Displacements of tunnel lining resulted from artificially accelerated gravitational force up to 40g of covered material used in model tests, were measured during centrifuge model tests. In model tests, Jumunjin Standard Sand with the relative density of 80 % and the zinc plates were used for the covered material and the flexible tunnel lining, respectively. Basic soil property tests were performed to obtain it's the property of Jumumjin Standard Sand. Shear strength parameters of Jumunjin Standard Sand were obtained by performing the triaxial compression tests. Direct shear tests were also carried out to find the mechanical properties of the interface between the lining and the covered material. Numerical analysis with the commercially available program of FLAC were performed to compare with results of centrifuge model experiment In numerical modelling. Mohr-Coulomb elasto-plastic constitutive model was used to simulaye the behavoor of Jumunjin Standard Sand and the interface element between the lining and the covered material was implemented to simulate the interaction between them. Compared results between model tests and numerical estimation with respect to displacement of the lining showed in good agreements.

Numerical analysis were performed to investigate the stability and internal movement of tunnel located beneath the base of abutment of bridge according to the method of supporting tunnel. Two supporting methods of the multi-staged grouting method with steel pipes and the large diameter of pipe supporting method were used in the centrifuge model tests. The slip form of model lining, specially built to simulate the process of tunnel excavating under the condition of accelerated g-level, was used in the centrifuge model tests. Four centrifuge model tests were performed, changing the supporting methods of the multi-staged grouting method with steel pipes and the large diameter of pipe supporting method and the location of model abutment base of bridge. For internal displacement of tunnel, movements of the crown. The left and the right sides of spring line were measured during the proceeds of excavating tunnel in centrifuge model tests. Test results were compared with numerically estimated values of internal displacement of tunnel by using the commercially available FEM software of PENTAGON-3D. It was found that they were in good agreements and the large diameter of pipe supporting method was more stable than the multi-staged grouting method with steel pipes with respect to the internal movement of tunnel.

A series of column test with a silty marine soil mixed with Jumunjin Standard Sand were performed to investigate the characteristics of settling and consolidation of non-plastic dredged soils. Column tests were carried out by using the separable column to measure the grain size distribution of consolidated layer. Column tests were performed with changing the mixing ratio of Jumunjin Standard Sand to the silty marine soil, initial water content of slurry and initial height of slurry. Height of interface of slurry was monitored during tests and grain size distribution tests were carried out after finishing tests. Influencing factors on the particle segregation, eventually to the characteristics of settling and consolidation of non-plastic soil, were analyzed on the thesis of test results. As results of column tests, the mixing ratio of sand to the silty marine soil and the initial water content of slurry were known to affect the characteristics of settling and consolidation resulted in significant particle segregation of slurry. Initial height of slurry was found not to affect seriously to particle segregation.

Recently, the public postal service of Korea confronts with business environment changes such as the opening of postal market and appearance of the domestic competitive enterprises. It is the current state that the public postal service of Korea should have a competitive edge by the productivity improvement of business processes. In this paper, we proposed new working tables for manual letter sorting which is one of the important process in mail center. We suggested standard working method and standard time in a mail center Based on these, we established the procedure for setting up a fair day's work in other mail centers. By the result of this research, we expect that the productivity of the mail sorting operation will be increased.