• Journal of Korean Society of Water and Wastewater
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• v.12 no.1
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• pp.45-51
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• 1998

The determinations of ammonia in water for drinking purpose served as one basis of judging the sanitary quality of water for a great many years. However, presently ammonia regulation varies depending on countries. In USA and Canada, ammonia is added to water for chloramination process. However, for korea, there is ammonia regulation of treated water in Korea which should not exceed 0.5mg/l as $NH_3-N$. There was a report exceeding 0.5mg/l of ammonia in chlorinated water when the famous drinking water contamination episode happened in the downstream of Nadong River, 1994. With lack of sewer distribution system and treatment plants of domestic wastes, many water treatment plants have a difficulty of complying with ammonia regulation in treated water. Breakpoint chlorination is usually performed to get rid of ammonia. The method which is allowed to measure ammonia in Korea is Phenate method. However, it would be undesirable to use Phenate method for measuring ammonia in chlorinated water if Phenate method would not differentiate ammonia from chloramine. A good possibility of interferences in measurement of ammonia exists because Phenate method include the step of the formation of chlorine and would not differentiate chloramine which is formed as a result of reaction between chlorine and ammonia. This study was on inaccuracy of Phenate method for measuring ammonia of chlorinated water when chloramine and ammonia coexist. This study found that Phenate method measured all chlormaine as ammonia. Ammonia measurement by ion chromatography confirmed this results. Finally, the result from this study suggests that ammonia measurement by Phenate method in chlorinated water should be revised accordingly.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.2
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• pp.77-85
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• 2010

Fingerprint image quality checking is one of the most important issues in on-line fingerprint recognition because the recognition performance is largely affected by the quality of fingerprint images. In the past, many related fingerprint quality checking methods have typically considered the local quality of fingerprint. However, It is necessary to estimate the global quality of fingerprint to judge whether the fingerprint can be used or not in on-line recognition systems. Therefore, in this paper, we propose both local and global-based methods to calculate the fingerprint quality. Local fingerprint quality checking algorithm considers both the condition of the input fingerprints and orientation estimation errors. The 2D gradients of the fingerprint images were first separated into two sets of 1D gradients. Then，the shapes of the PDFs(Probability Density Functions) of these gradients were measured in order to determine fingerprint quality. And global fingerprint quality checking method uses neural network to estimate the global fingerprint quality based on local quality values. We also analyze the matching performance using FVC2002 database. Experimental results showed that proposed quality check method has better matching performance than NFIQ(NIST Fingerprint Image Quality) method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.9-14
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• 2016

The Korea Communication Commission(KCC) measures communication qualities of mobile phones' voice calls, mobile internet, and broadband internet to provide quality communication services. It particularly focuses on measuring qualities of mobile internet data that is on the rise in terms of usage. However, existing quality measurement simply measures the speed of mobile communication through data without providing much information to users and does not disclose measured data, making it hard for individuals to objectively determine their communication quality. Thus, to improve such problems, the author suggests a system that measures qualities of mobile communication through Android. The method guarantees user convenience and reliability and improved mobile communication by making it easy for users to select the quantity of data to be used. It also saves the current GPS obtained through GPS module or mobile communication network and transfers measured data to servers so that the data can be processed into new information and be reinterpreted.

• Journal of Veterinary Clinics
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• v.39 no.3
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• pp.114-120
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• 2022

The purpose of this study is to examine the status of quality control using multipurpose phantom of ultrasound equipment used in hospital of veterinary college in South Korea by using ATS-539 multipurpose phantom so as to examine quantitative and objective new image evaluation method. Specialists discussed and analyzed multipurpose phantom images acquired by using convex transducer of 10 ultrasound imaging devices, currently used in 9 veterinary colleges, at 4.0-6.0 MHz. Total 8 items that can be measured with ATS-539 multipurpose phantom including dead zone, vertical and horizontal measurement, axial/lateral resolution, sensitivity, focal zone, functional resolution and gray scale/dynamic range were evaluated. For qualitative evaluation, valid decisions were made based on dead zone, axial/lateral resolution, and gray scale/dynamic range which are resolution index, and coefficient of variation (COV) and blind referenceless image spatial quality evaluator (BRISQUE) were found to increase objectivity. As a result of experiment, all the targeted ultrasonic devices were found appropriate from qualitative evaluation items of dead zone, axial/lateral resolution, and gray scale/dynamic range. In other evaluation items, they were found to be appropriate from focal zone and vertical measurement of quantitative evaluation while inappropriate from horizontal measurement, sensitivity, and functional resolution. COV value was 0.12 ± 0.04, and BRISQUE value was 47.77 ± 2.77, both analysis results show that the noise level of all ultrasonic devices was located within tolerance range. Upon image examination using ATS-539 multipurpose phantom, they were 100% appropriate with inspection standards of dead zone, axial/lateral resolution, and gray scale/dynamic range, and besides, focal zone and functional resolution can be used as evaluation items. In the field of veterinary medicine, 8 standard items using ATS-539 multipurpose phantom and image evaluation items using COV and BRISQUE can be used as standards for quality control of ultrasonography machine.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1273-1279
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• 2006

In this paper, we address the design of adaptive handover schemes based on the signal strength measurement for cellular communications systems. Conventional handover algorithms, which are based only on the downlink measurement, cannot guarantee the required uplink quality because uplink channel can differ greatly from downlink channel quality. Therefore, we proposes a new suboptimal adaptive handover algorithm that considers both the uplink and downlink channel quality in order to achieve the best cell selection gains when there is a wide difference between the uplink and downlink signal quality. Simulation results show that the proposed scheme achieves better performance compared to conventional handover schemes.

• Journal of Welding and Joining
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• v.12 no.3
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• pp.109-117
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• 1994

Spot welding has wide used with a high work efficiency in the automotive and aerospace industries. Up to the present, the technique mainly used to test spot welds on production lines has been entirely depended upon destructive chisel or peel testing. Therefore, it's being very important assignment to secure the NDE technique which can be evaluate spot weld quality with more efficiency and high reliability. This paper discusses the feasibility of UNDE techniques to evaluate spot weld quality. For the sake of the approach to the quantitative measurement of nugget diameter and the discrimination of a the corona bond from nugget, ultrasonic c-scan image and distribution of reflective echo amplitude was measured by immersion method with the mechanical and the electronic scanning of point-focussed ultrasonic beam(25 MHz). As the results of this study, corona bond which is the most dangerous types of interface defects can be successfully detected, as well as expulsion and voids. Ultrasonic testing results were confirmed and compared by optical microscope and SAM(Scanning Acoustic Microscope) observation of the spot-weld cross section. The results show that the nugget diameter can be successfully measured with the accuracy of 0.8 mm.

• Journal of Magnetics
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• v.12 no.4
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• pp.149-151
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• 2007

The AlCrN films were grown by RF reactive sputtering method under the selected conditions. The Cr concentration was varied by the number of Cr pieces placed on the Al target. The sample quality has been studied by XRD, Auger spectroscopy, optical absorption and electrical resistant measurements. The XRD and Auger results show that the samples consist of a major phase with the $Al_{1-x}Cr_xN$ formula, which has a hexagonal structure, and a few percents at. of oxygen, which may form $Al_2O_3$. There exist the Cr clusters in the samples with high concentration of Cr. The optical absorption measurement provides the information about the band gap that relates strongly to the quality of samples. The quality of samples is also clearly reflected in electrical measurement, i.e., the temperature dependence of resistance exhibits a semiconductor characteristic only for the samples that have no Cr cluster. In these cases, the values of ionization energies $E_a$ can be derived from R(T) plots by using the function R(T) = Ro exp $(E_a/k_BT)$.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.257-264
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• 2006

In order to evaluate the application of Algae Online Analyzer (AOA), an instrument of automatic measurement of chlorophyll a concentration, was tested and compared with the acetone extraction method on the basis of microscopic counting of phytoplankton in field water (Paltang Reservoir). We simultaneously conducted AOA operation and extraction method with the same water sample, to compare both results of chlorophyll a measurement. Phytoplankton were enumerated by inverted microscope with the Sedgwick-Rafter chamber, and classified into the genus or species. According to the AOA measurement, the diatom most (83.6%) strongly contributed to the total chlorophyll a concentration, followed by chlorophyceae> cyanophyceae>cryptophyceae. Overall, the results of both AOA and extraction method showed a similar trend and significant correlation (r=0.87, n=302, p<0.001), however, there were some differences according to the season and species. In particular, the relationship between AOA Chl-a density of the diatom (r=0.73, p=0.010) and cyrptophyceae (.=0.83, p=0.00154) were siginificant, while chlorophyceae (r= -0.13) and cyanophyceae (r= -0.16) showed no clear relationship during the study period. Although we can not fully understand why there was difference between both mothods, AOA application for alarming algal bloom and water quality management during the algal bloom appears to be very relevant. However, the further study or technical upgrade of AOA measurement is required, especially in the case of low density of phytoplankton or species-specific measurement.

• Journal of radiological science and technology
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• v.28 no.2
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• pp.111-115
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• 2005

The quality of image from the system that creates medical images by using X-ray depends on the various different reasons such as the X-ray generator, the subject and the image transmission medium. In other words, thereare various factors existing that can influence on the quality of image from the moment when the X-ray is generated and until the final image is created. Therefore, the operator who creates images at the clinical site should make continuous evaluation and observation from the final image. There are various methods of evaluating the medical images, but it is assumed that the MTF measurement method can be suitable for measuring actual or effective resolution. So in this study, the MTF measurement method by using X-ray film has been avoided and the MTF features according to the deterioration of the X-ray system have been measured by using the software (the program used Borland C++ builder software and LEAD tools software) that can measure the MTF of the digital medical images. As the result of this measurement, it has been found out through the MTF graph that the resolution and sharpness from the old x-ray generator with a many years of using and many numbers of times of using were deteriorated for the quality of image comparing to those from the new system. Also a simple and easy measurement method for the MTF from the digital medical images can be obtained in this study.

• Journal of Korean Society for Quality Management
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• v.23 no.2
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• pp.1-9
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• 1995

Two user groups, expert and non-expert, are sampled to measure the image quality of G3 facsimile. A ITU-TS tset chart No. 2 has been transmitted among some selected cities and evaluated by user groups. Their subjective evaluation to the image quality is quantified by Mean Opinion Score method. There is highly significant difference in the image quality between expert and non-expert. From modified logit model, it is concluded that there is no significance in two considered factors, the effects of the number of links and transmission time. The derived percent curves show that 80% of non-experts(90% of expert) is considering the image quality of G3 facsimile "fair, good, or excellent".