• Journal of Environmental Science International
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• v.28 no.10
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• pp.887-898
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• 2019

Rehabilitation work is required to increase well productivity, which decreases with the elapsed time of pumping owing to the clogging of the water well. Clogging causes not only a reduction in the well productivity but also a deterioration of the water quality. For unclogging and rehabilitating wells, several techniques are used such as brushing, air surging, surge blocks, and gas impulse. In this study, the high-pressure air impulse technique, which effectively and economically rehabilitates wells, was applied to a riverbank filtration site in Korea for the same objective. At most of the wells, the hydraulic parameters (transmissivity, storage coefficient, and specific capacity) were increased by the application of the high-pressure air impulse technique. The well loss change values also indicate an increase in the hydraulic parameters by the air impulse implementation. Thus, the high-pressure air impulse technique can be efficiently and economically applied to water and riverbank filtration wells for rehabilitating the decreased productivity.

• Structural Engineering and Mechanics
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• v.42 no.3
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• pp.363-381
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• 2012

This study is aimed at providing an efficient analytical model to obtain pressure- impulse diagram of one-way reinforced concrete slabs subjected to different shapes of air blast loading using single degree of freedom method (SDOF). A tri-linear elastic perfectly plastic SDOF model has been used to obtain the pressure-impulse diagram to correlate the blast pressure and the corresponding concrete flexural damage. In order to capture the response history for the slab, a new approximately SDOF method based on the conventional SDOF method is proposed and validated using published test data. The influences of pulse loading shape on the pressure-impulse diagram are studied. Based on the results, a pressure-impulse diagram generation method using SDOF and an analytical equation for the pressure-impulse diagram is proposed to different damage levels and different blast loading shapes.

• Journal of Advanced Navigation Technology
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• v.9 no.1
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• pp.1-8
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• 2005

In this paper, an impulse generator for UWB(Ultra Wide-band) technique with great possibility to be adopted as a next generation indoor WLAN(Wireless Local Area Network) has been designed by using SRD(Step Recovery Diode). Design goal is to design an impulse generator with simple structure, low cost, small size, and high performance. The impulse generator satisfied by FCC's regulation ( frequency range: 3.1~10.6 GHz, limit of power level: -41.25 dBm ) has been simulated by using ADS(Advanced Design System) which is the trade name of the Agilent Technologies. The output power of the impulse generator has been explained separately for single and multi band purposes, respectively.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.397-401
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• 2011

The response of lightning impulse voltage was explored in dielectric liquids employing hydrodynamic modeling with three charge carriers using the finite element method. To understand the physical behavior of discharge phenomena in dielectric liquids, the response of step voltage has been extensively studied recently using numerical techniques. That of lightning impulse voltage, however, has rarely been investigated in technical literature. Therefore, in this paper, we tested impulse response with a tip-sphere electrode which is explained in IEC standard #60897 in detail. Electric field-dependent molecular ionization is a common term for the breakdown process, so two ionization factors were tested and compared for selecting a suitable coefficient with the lightning impulse voltage. To stabilize our numerical setup, the artificial diffusion technique was adopted, and finer mesh segmentation was generated along with the axial axis. We found that the velocity from the numerical result agrees with that from the experimental result on lightning impulse breakdown testing in the literature.

• Journal of Distribution Science
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• v.20 no.5
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• pp.49-64
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• 2022

Purpose: This research aims to determine the quality of online store designs that make consumers who use online market board applications have the urge to make impulse buying. This research was conducted because impulse buying is the most common buying behavior. Research design, data and methodology: This research used non-probability sampling. The sample size was 195 respondents from the distribution and service industries by applying a purposive sampling technique. The data collection technique employed a questionnaire distributed online according to predetermined criteria: mobile device users who accessed the online market board application and made at least one purchase in the last six months. The data analysis method utilized was structural equation modeling (SEM). Results: The findings revealed that usability, functionality, and sociability factors affected hedonic and utilitarian search. Furthermore, these findings proved that hedonic search affected impulse buying drives. In contrast, the utilitarian search did not affect impulse buying drives. Conclusions: The usability, functionality, and sociability factors supported hedonic and utilitarian searches. Consumer information security increased consumer confidence in an online store because it was considered to protect matters related to their privacy. The hedonic search also increased impulse buying drives. Consumers prefer to use their spare time to search through online market board applications, which provide many attractive promos.

• Journal of Distribution Science
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• v.19 no.7
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• pp.101-111
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• 2021

Purpose: The main purpose of this research is to examine the effect of impulse buying tendencies toward impulse buying, which is mediated by an urge to buy and moderated by the gender of the retail customers. Research design, data and methodology: This study uses a survey design. The sample consisted of several mall customers in Yogyakarta. Purposive sampling was used as the sampling technique. Data collection was carried out in two ways, distributing questionnaires online and directly giving questionnaires to mall customers. Results: The results of data analysis using structural equation modeling show that: 1). Impulse buying tendencies have a positive and significant effect on the urge to buy and impulse buying, 2). The effect of impulse buying tendencies on impulse buying were mediated by an urge to buy and moderated by gender. Conclusions: Theoretical implications of this research strengthen the concept/theory concerning the relationship of the impulse buying tendencies, urge to buy and impulse buying. The results of the study have some managerial implications. It can be used to reference retail store business in increasing the volume of retail customers purchases through impulse buying. The retail businesses can increase impulse buying which will trigger impulsive purchases and the company's sales and profitability

• Journal of Information Processing Systems
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• v.9 no.1
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• pp.89-102
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• 2013

The paper presents a fuzzy based impulse noise filter for both gray scale and color images. The proposed approach is based on the technique of boundary discriminative noise detection. The algorithm is a multi-step process comprising detection, filtering and color correction stages. The detection procedure classifies the pixels as corrupted and uncorrupted by computing decision boundaries, which are fuzzified to improve the outputs obtained. In the case of color images, a correction term is added by examining the interactions between the color components for further improvement. Quantitative and qualitative analysis, performed on standard gray scale and color image, shows improved performance of the proposed technique over existing state-of-the-art algorithms in terms of Peak Signal to Noise Ratio (PSNR) and color difference metrics. The analysis proves the applicability of the proposed algorithm to random valued impulse noise.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.2
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• pp.151-158
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• 2004

In this paper, an inverse filtering technique for the digital filter model is proposed. This technique enables us to obtain a stable non-causal m inverse filter by transforming (approximating) it to a causal stable inverse system. In practice, a causal FIR approximation to this inverse filter is proposed. It can be shown that the impulse response of the inverse filter for all-pass systems is simply the mirror image of the impulse response for the system. Specially, due to this symmetric property of the impulse response of all-pass systems, the proposed technique is more useful for all-pass systems than other systems. In order to illustrate the proposed inverse filtering technique, four examples are presented. Two of them are for all-pass filters. The other two examples are for IIR and FIR filters. Also, computer simulations demonstrate that the proposed technique works very well.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.596-602
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• 2001

Structures in current use are required of weight reduction and strength in many instances. This naturally necessitates frequent applications of composite materials in many areas. Elastic constants are one of key parameters in determining design guidelines for the specific applications of particular materials. In this research two vibratory techniques (acoustic resonance method and impulse technique)are utilized to evaluate elastic constants. Both techniques are suitable for the measurements of dynamic elastic constants. The Impulse technique provides a quick method for the measurement while the acoustic resonance method produces the values of elastic constants which agree better with theoretical values.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.310-319
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• 2017

This paper introduces the method how to measure the thrust in impulse facility. In a Facility having such a short duration time of steady flow, there's no time to reach a steady state of the forces acting on model so that the test model vibrates until the end of the flow. The forces exerted on an engine exist with vibration so that the usual force balance can not be used. SWFB(Stress Wave Force Balance) technique is utilized in a shock tunnel to get the thrust. As an example, a model force balance has been calculated its strain against impulse force by using FEM(Finite Element Method). A transfer function between the impulse force and strain has been obtained by the way of de-convolution.