• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2005.05a
• /
• pp.413-418
• /
• 2005

This paper proposes a measurement method for the surface of micro-parts by using AFM(Atomic Force Microscope). To this end, two techniques are presented to extend the capacity of AFM. First, the measurement range is extended by using an image matching method based on correlation coefficients. To account for the inaccuracy of the coarse stage implemented in AFM's, the image matching technique is applied to two neighboring images intentionally overlapped with each other. Second, a method to measure the shape of relatively large specimen is presented by using the inherent trigger mechanism due to the atomic force. The proposed method is proved effective through a series of experiments.

• 전기의세계
• /
• v.31 no.3
• /
• pp.204-208
• /
• 1982

The objective of this paper is to present a digital method for improving the lateral resolution of the B-scan images in the medical applications of ultrasound. The method is based upon a mathematical model of the lateral blurring caused by the finite beam width of the transducers. This model provides a simple method of applying a recursive scheme for image restoration with fast computation time. The point spread function (P.S.F.) can be measured by the reflective signals after scanning the small pins located along the depth of interest. From the measured P.S.F., one can compute the coefficient matrices of the inverse discrete-time dynamic state variable equation of the blurring process. Then, a recursive scheme for deblurring is applied to the recorded B-scan to improve the lateral resolution. One major advantage of the present recursive scheme over the transform method is in its applicability for the space-variant imaging, such as in the case of the rotational movement of transducer.

• Advances in concrete construction
• /
• v.17 no.1
• /
• pp.37-43
• /
• 2024

In this paper, boundary layer flow is observed through stretching cylinder exponentially with non-linear velocity. This cylinder is rested in porous medium. Appropriate similarity transformation is employed for the conversion of governing PDEs into ODEs. To compute the problem and solution series numerical method is applied and evaluated by using finite difference Keller-Box method. The velocity ratio, permeability parameter, Reynold number is figure out to examine the effect of on velocity profile. Fluid velocity and skin friction coefficient goes down with increment of Reynold number and permeability parameter. While reverse behavior is reported for velocity ratio. The results are validated with earlier investigations and found very well.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.7
• /
• pp.849-861
• /
• 1997

In this study, the effect of hole geometry of the cooling system on the flow and temperature field was numerically calculated. The finite volume method was employed to discretize the governing equation based on the non-orthogonal coordinate with non-staggered variable arrangement. The standard k-.epsilon. turbulence model was used and also the predicted results were compared with the experimental data to validate numerical modeling. The predicted results showed good agreement in all cases. To analyze the effect of the discharge coefficient for slots of different length to width, the inlet chamfering and radiusing holes were considered. The discharge coefficient was increased with increment of the chamfering ratio, radiusing ratio and slot length to width and also the effect of radiusing showed better result than chamfering in all cases. In order to analyze the difference between the predicted results with plenum region and without plenum region, the velocity profiles of jet exit region for a various flow conditions were calculated. The normal velocity components of jet exit showed big difference for the low slot length to width and high blowing rate cases. To analyze the flow phenomena injected from a row of inclined holes in a real turbine blade, three dimensional flow and temperature distribution of the region including plenum, hole and cross stream with flow conditions were numerically calculated. The results have shown three-dimensional flow characteristics, such as the development of counter rotating vortices, jetting effect and low momentum region within the hole in addition to counter rotating vortex structure in the cross stream.

• 한국생물공학회:학술대회논문집
• /
• 2005.04a
• /
• pp.65-66
• /
• 2005

Anaerobic digestion is one of the well-known methods for biological treatment handling of concentrated organic matter such as swine $wastewater.^{1)} The anaerobic digestion can reduce organic loading but also hydrolyze non-biodegradable organic $matter.^{2)}$ The feces from the scrapper-type barn are usually collected to make compost and the urine is discarded with swine-slurry wastewater by ocean-dumping or treated by biological methods. The lagoon, aerobic digestion, anaerobic digestion, SBR, $A^{2}/O$, and UCT have been applied for treating swine $wastewater.^{3)} In this study, as a result of the analysis of swine wastewater, the total and soluble chemical oxygen demand was 130g/L and 60g/L, respectively. And the volatile fatty acid as chemical oxygen demand equivalent was 45g/L, which was 75% of soluble chemical oxygen demand. Before everything else, ammonia nitrogen concentration was 6.5 g/L. From biochemical acidogenic potential test, it was concluded that the enhanced acidification process to manage swine waste should be operated in the ammonia nitrogen concentration of less than 1.2 g/L. In the result of seeding ratio experiments with artificial $wastewater^{4)}, the lag period of acidogens was taken the long time because of the inhibition by the $ammonia^{5)}$, however no difference of period by the seeding ratio was not shown. The Haldane-based biokinetics were also evaluated using a method of fourth order Runge-Kutta $approximation.^{6,7)}$ The nonlinear least squares (NLLS) method with a 95% confidence interval was also used. The ranges of maximum microbial growth rate, ${/mu_{max}}$, and half saturation coefficient, $K_{s}$, for acidogenesis of various seeding ratio with artificial wastewater were 6.1 ~ 12.6 $d^{-1}$ and 45,000 ~ 53,500 mg glucose/L, respectively. Also, the methanogenic microbial yield coefficient, Y, and microbial decay rate coefficient, $k_{d}$, and inhibition substrate concentration, $K_{si}$, for the reactors were determined to be 0.32 ~ 0.465 ${/mu}g$/mg glucose; 0.42 ~ 1.01 $d^{-1}$ and 51,500 ~ 55,600 mg glucose/L, respectively.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.6
• /
• pp.2109-2124
• /
• 1991

A simulation program is developed to analyse the performance of an axial flow turbine stage based on the meanline prediction method. The gradient projection method is utilized to minimize the aerodynamic losses under the specified constraints on such as flow coefficient, total pressure ratio, stage power and blade loading coefficient. After obtaining the optimum point for minimizing the stage loss, a sensitivity analysis is carried out ground the optimum point to find the effects of the design variables and the design constraints on the stage performance. The result of the senitivity analysis under a constant blade loading coefficient shows that the total loss is more sensitive to the mean diameter, the absolute flow angle at nozzle outlet, the relative flow angle at rotor outlet and the axial mean velocity compared to the chords and the pitches. Moreover, the design constraints on the degree of reaction at root and the blade length-to-diameter ratio are found to be most influencial on the maximization of the overall aerodynamic efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.5
• /
• pp.1134-1140
• /
• 2004

In this paper, we investigated the effect of cross phase modulation(XPM) on compensation for WDM channel distortion due to chromatic dispersion, self phase modulation and XPM as a function of fiber dispersion coefficient and modulation format in 320 Gbps WDM systems. The considered WDM transmission system is based on mid-span spectral inversion(MSSI) compensation method, which has highly nonlinear dispersion shifted fiber(HNL-DSF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that the maximum channel input power resulting 1 dB eye opening penalty is reduced due to XPM effect on channel distortion, even if MSSI method was applied to WDM system. But, we confirmed that the effect of XPM on channel distortion becomes decrease as fiber dispersion coefficient of WDM system becomes larger. Futhermore, we confirmed that NRZ is better than RZ as a modulation format for similarly compensating overall WDM channels in WDM system with large fiber dispersion coefficient in order to minimize the effect of the XPM on channel distortion.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.41 no.1
• /
• pp.118-127
• /
• 2018

Recently, service quality must reflect several demands of customers who show rapid and various changes so as to be compared with the past. So, objective and rapid measuring methods for service quality are necessary. For them, first of all, service company must calculate their standard of service quality accurately by measuring service quality exactly. Kano classified the degree of influence that is the degree of correspondence of the quality attributes of products and services to the subjective satisfaction of customers. As a result, the types of qualities are classified as attractive, must be, one dimensional, and indifference attributes. They have been widely used quality attributes in various industrial fields up to now. However, Kano model has a limit that it ignores the characters of the next frequent numbers even though there are not much gap comparing to the most frequent number in the questionnaire answers. The limit is attributed to the character of Kano model that the most frequent number is accepted as the only quality character. Timko calculated the customer satisfaction coefficient by using Kano's method and studied the differences in quality character by classifying the quality characteristics in a graphical way through the relationship between the satisfaction and the dissatisfaction coefficient. In this study, we used the quality level determination method of the 7-point Likert scale, which takes the weight into account, to complement the deficiencies of the existing Kano model. We also developed and applied a Potential Satisfaction Level (P) and Potential Customer Demand Improvement (PCDI) Index to present a new approach to the determination of service quality attributes. To measure the level of potential service satisfaction and to understand the degree of improvement, we collected specimens of 51 participants who has been trained in the National Strategy Business Training Program, which has been managed by government agent, and analyzed the results.

• Convergence Security Journal
• /
• v.18 no.5_1
• /
• pp.59-66
• /
• 2018

The performance of a network intrusion detection system using the machine learning method depends heavily on the composition and the size of the feature set. The detection accuracy, such as the detection rate or the false positive rate, of the system relies on the feature composition. And the time it takes to train and detect depends on the size of the feature set. Therefore, in order to enable the system to detect intrusions in real-time, the feature set to beused should have a small size as well as an appropriate composition. In this paper, we show that the size of the feature set can be further reduced without decreasing the detection rate through using Pearson correlation coefficient between features along with the multi-objective genetic algorithm which was used to shorten the size of the feature set in previous work. For the evaluation of the proposed method, the experiments to classify 10 kinds of attacks and benign traffic are performed against NSL_KDD data set.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.41 no.4
• /
• pp.34-41
• /
• 2018

This paper studied balanced regional development focused on employment in Korea, by analyzing regional disparity between regional and industrial employment. A Gini-coefficient decomposition method and Panel Granger causality test were conducted, using raw data of the Census on Establishments reported by the Statistics Korea. The regional and industrial disparity of employment, based on the Gini-coefficient decomposition method, have increased by year. However, the growth rates of disparity are on the decrease. Most of employment disparity occurred from regional disparity between SMA (Seoul Metropolitan Area) and Non-SMA. Industrial disparity are occurred mainly by the service industry. The amount of contribution to the whole disparity of inter/intra regional employment was differed by each industrial sector. Also the causal relationship between employment growth of manufacture and that of service industry was analyzed by Panel Granger causality test. In national level, the employment growth in manufacture industry has conduced that in service industry. On the other hand, in the Non-SMA, only the employment growth in manufacture industry has augmented that in service industry. In conclusion, to reduce employment disparity, the strategy for balanced regional development should be emphasized. Different strategies are needed across regions and industries. Basically creating new job in the Non-SMA is inevitable. In view of stable employment, manufacture industry is more desirable rather than service industry.