• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.25-34
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• 2012

In this study, in the process of testing before the release of the software products designed, software testing manager in advance should be aware of the testing-information. Therefore, the effective learning effects perspective has been studied using the NHPP software. The finite failure nonhomogeneous Poisson process models presented and applied property of learning effect based on truncated time and delayed S-shaped software reliability. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is greater than autonomous errors-detected factor that is generally efficient model can be confirmed. This paper, a failure data analysis was performed, using time between failures, according to the small sample and large sample sizes. The parameter estimation was carried out using maximum likelihood estimation method. Model selection was performed using the mean square error and coefficient of determination, after the data efficiency from the data through trend analysis was performed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.143-148
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• 2023

Among the characteristics of SRM, due to nonlinearity, it is difficult to properly operate to form maximum torque and minimum torque pulsation. In addition, in the case of fixed switching angle control, torque formation according to speed variation is unstable, thereby reducing efficiency. Therefore, active switching angle control according to speed variation is required. Therefore, active switching angle control according to speed variation is required. In this paper, a method for improving driving performance by reducing torque ripple by automatic control of the advance angle and increasing output torque was sought from the problem caused by the nonlinearity of the SRM. In addition, the optimal operation of SRM due to the switching variable according to the performance of the hysteretic current controller was examined.

• Explosives and Blasting
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• v.40 no.2
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• pp.25-34
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• 2022

Recently, there has been an increasing number of cases of improving constructability by using electronic detonators with precise delay time in tunnel blasting sites. This case is a case of conducting test blasting using with non-electric detonator and electronic detonator at the site of 『Seoul Metropolitan Area Express Railroad Route A Private Investment Project Section 00』 that requires careful management of vibration and noise. Although this site was designed with a non-electric detonator, it was attempted to improve the advance rate and control vibration and noise by mixing the non-electric detonator and the electronic detonator due to the decrease in the advance rate. As a result of the blasting, the target value was achieved with an advance rate of about 85% and a maximum measured value of vibration and noise is 0.215cm/sec and 73.22dB(A) which were measured below regulatory standards. As blasting works in downtown areas, it is necessary to designate measurement and management objects to continuously manage vibration and noise.

• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.698-704
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• 2018

When the new ammunition is designed, it is necessary to confirm in advance how long the target distance is depends on the shape and weight of the designed ammunition. Therefore we can use commercial software such as PRODAS to predict the target distance in the design stage. This commercial software has aerodynamic data for various ammunition shape and calculates the target range by calculating the kinetic equations of the ammunition using the aerodynamic data most similar to the designed ammunition. The ammunition for predicting the target distance through software such as PRODAS is a non-guided ammunition that has no control after launch but the glide type ammunition is guided and control ammunition. So it is predicts the state of ammunition after the launch. A new type of simulator is needed to analyze the maximum range and to verify the onboard guided and control algorithm. The simulator constructed in this paper is an optimized simulator for glide type ammunition. Unlike unmanned aircraft and guided missiles. The rotation characteristics of the ammunition are considered and the navigation initialization algorithm is applied. The constructed simulator confirmed the performance by performing maximum range analysis of glide type ammunition.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.119-124
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• 2003

Despite rapid technological advance and increased automation facilities, many jobs and activities in our living require manual materials handling(MMH). These include wide variety of activities such as moving things, lifting bags. boxes or cartons, etc. Many studies found that handle could affect on maximum acceptable weight of lifting, but there were few studies f3r the effects of work posture and coupling in lifting tote box. This study performed that ten male college students were required to lift a tote box with and without handle for three postures (bending, straight, right angle posture). From the experiment, following results were obtained. (1) MVC reduced maximum 23% by type of handle. (2) MVC was highest in straight posture, but was lowest in right angle posture. (3) As a result of ANOVA, MVC paid attention to posture and coupling. (p<0.01) (4) To all handle types, biceps brachii activity was increased in right angle posture. but reduced in straight posture. (5) To all posture, biceps brachii activity was most lively in no handle. The results of MVC measurement, subjective rating, EMG analysis, statistic analysis showed that maximum acceptable weight of lifting was influenced by type of handle and straight posture was more comfortable than other postures. Based on these results, it was concluded that acceptable weight of lifting has to differ for work posture and coupling.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.457-471
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• 2015

A domestic cutterhead with the diameter of 3.6 m was designed and manufactured in this study. Then, it was attached to an existing earth-pressure balanced shield TBM to excavate a cable tunnel with the length of 1,275 m. Especially, the procedures for TBM cutterhead design and its corresponding performance prediction were also summarized. From field data analyses of the refurbished shield TBM, its maximum advance rate was recorded as 14.4 m/day. Penetration depths of disc cutters were found to be approximately 4 mm/rev, which is equal to the maximum penetration depth designed for the strongest rock strength condition in the target tunnel. Every TBM operating thrust and cutter normal force during TBM driving was much smaller than their corresponding maximum capacities. When cutter acting forces recorded in the field were analyzed, their prediction errors by the CSM model were very high for weak rock conditions. In addition, rock strength showed very close relationships with cutter normal force and penetration depth.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.172-178
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• 2002

One of the ever-increasing demands on the performances of heterodyne interferometers is to improve the measurement resolution, of which current state -of-the-art reaches the region of sub-nanometers. So far, the demand has been met by increasing the clock speed that drives the electronics involved fur the phase measurement of the Doppler shift, but its further advance is being hampered by the technological limit of modem electronics. To cope with the problem, in this investigation, we propose a new scheme of phase -measuring electronics that reduces the measurement resolution without further increase in clock speed. Our scheme adopts a super-heterodyne technique that lowers the original beat frequency to a level of 1 MHz by mixing it with a stable reference signal generated from a special phase- locked-loop. The technique enables us to measure the phase of Doppler shift with a resolution of 1.58 nanometer at a sampling rate of 1 MHz. To avoid the undesirable decrease in the maximum measurable speed caused by the lowered beat frequency, a special form of frequency up-down counting technique is combined with the super-heterodyning. This allows performing required phase unwrapping simply by using programmable digital gates without 2n ambiguities up to the maximum velocity guaranteed by the original beat frequency.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.1-10
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• 1998

Testing high reliability devices under nomal operating condition is difficult, because the devices are not likely to fail in the relatively short time available for tests. For most applications it is necessary to accelerate the causes of failure by increasing a stress above its nomal value. Previous accelerated life test(ALT) plans have shown how to find optimum allocation, lowest stress and sample size subject to minimizing the variance of mean life estimator. In these ALT plans, the highest acceptable test-stress was assumed to be specified in advance by the experimenter but there is no guidance for selecting it. This assumption is, however, inappropriate for many applications. Testing devices at too-high stress levels can invalidate the extrapolation model, or introduce failure mechanisms that are not anticipated under nomal operating conditions. In this paper, we propose new 4:2:1 compromise plans using Min-Max method to minimize this risk and present minimized test-stress levels(max, middle, min), and find sample allocation based on Min-Max 4:2:1 compromise plans. In result, we compare previous 4:2:1 compromise plans specified maximum test-stress with Min-Max 4:2:1 compromise plans minimized maximum test-stress.

• Journal of the Korea Society of Computer and Information
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• v.16 no.5
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• pp.153-162
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• 2011

The minimum cut problem is to minimize c(S,T), that is, to determine source S and sink T such that the capacity of the S-T cut is minimal. The flow-based algorithm is mostly used to find the bottleneck arcs by calculating flow network, and does not presents the minimum cut. This paper suggests an algorithm that simply includes the maximum capacity vertex to adjacent set S or T and finds the minimum cut without obtaining flow network in advance. On applying the suggested algorithm to 13 limited graphs, it can be finds the minimum cut value $_{\min}c$(S, T) with simply and correctly.

• Journal of Information Processing Systems
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• v.14 no.3
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• pp.666-679
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• 2018

The discrete wavelet transform (DWT) has good multi-resolution decomposition characteristic and its low frequency component contains the basic information of an image. Based on this, a fragile watermarking using the local binary pattern (LBP) and DWT is proposed for image authentication. In this method, the LBP pattern of low frequency wavelet coefficients is adopted as a feature watermark, and it is inserted into the least significant bit (LSB) of the maximum pixel value in each block of host image. To guarantee the safety of the proposed algorithm, the logistic map is applied to encrypt the watermark. In addition, the locations of the maximum pixel values are stored in advance, which will be used to extract watermark on the receiving side. Due to the use of DWT, the watermarked image generated by the proposed scheme has high visual quality. Compared with other state-of-the-art watermarking methods, experimental results manifest that the proposed algorithm not only has lower watermark payloads, but also achieves good performance in tamper identification and localization for various attacks.