• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1516-1524
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• 2020

Climate change is expected to affect not only availability and quality of water, the valuable resource of human life on Earth, but also ultimately public health issue. A six-year monitoring (total 20 times) of Escherichia coli O157, Salmonella enterica, Legionella pneumophila, Shigella sonnei, Campylobacter jejuni, and Vibrio cholerae was conducted at five raw water sampling sites including two lakes, Hyundo region (Geum River) and two locations near Water Intake Plants of Han River (Guui region) and Nakdong River (Moolgeum region). A total 100 samples of 40 L water were tested. Most of the targeted bacteria were found in 77% of the samples and at least one of the target bacteria was detected (65%). Among all the detected bacteria, E. coli O157 were the most prevalent with a detection frequency of 22%, while S. sonnei was the least prevalent with a detection frequency of 2%. Nearly all the bacteria (except for S. sonnei) were present in samples from Lake Soyang, Lake Juam, and the Moolgeum region in Nakdong River, while C. jejuni was detected in those from the Guui region in Han River. During the six-year sampling period, individual targeted noxious bacteria in water samples exhibited seasonal patterns in their occurrence that were different from the indicator bacteria levels in the water samples. The fact that they were detected in the five Korea's representative water environments make it necessary to establish the chemical and biological analysis for noxious bacteria and sophisticated management systems in response to climate change.

• Geophysics and Geophysical Exploration
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• v.2 no.2
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• pp.104-111
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• 1999

As a practical developing step of electromagnetic (EM) tomography technique, we quantitatively analyzed the effects of borehole fluid and casing on the borehole EM responses. The EM response turns out to have nothing to do with the property of the borehole fluid except in the close vicinity of the transmitter, which shows the wide perspective of the application of borehole EM. Single-hole responses in the presence of the steel casing throughly reflect those of the casing itself since its extremely high induction number or shallow skin depth. EM responses through steel casing do show the information of the host medium. In the near field region which corresponds to low frequency or the vicinity of the borehole, however, we can not separate the signal containing the information of the host from that of casing. Otherwise, the severe attenuation of energy in the casing at high frequencies renders the signal undetectable. The optimum frequency is, therefore, to be chosen to extract the information of the host considering both the property of the casing and the skin depth of the medium and the practical technique to determine the casing property through single-hole measurements is required.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.3 no.1
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• pp.18-25
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• 1978

The 1/f noise spectrum of short-circuited output drain current due to the Shockley-Read-Hal] recombination centers with a single lifetime in homogeneous nondegenerate MOS-field effcte transtors with n-type channel is calculated under the assumptions that the quasi-Fermi level for the carriers in each energy band can not be defined if we include the fluctuation for time varying quantities. and so 1/f noise is a majority carrier effect. Under these assumptions the derived 1/f noise in this paper show some essential features of the 1/f noise in MOS-field effect transistors. That is, it has no lowfrequency plateau and is proportionnal to the channel cross area A and to the driain bias voltage Vd and inversely proportional to the channel length L3 in MOS field effect transistors. This model can explain the discrepancy between the transition frequency of the noise spectrum from 1/f- response to 1/f2 and the frequency corresponding to the relaxation time related to the surface centers in p-n junction diodes. In this paper the results show that the functional form of noise spectrum is greatly influenced by the functional forms of the electron capture probability cn (E) and the relaxation time r (E) for scattering and the case of lattice scattering show to be responsible for the 4 noise in MOS fold effect transistors. So we canconclude that the source of 1/f noise is due to lattice scattering.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.12
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• pp.78-89
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• 1999

Previous wavelet network structures are determined by considering the relationship between wavelet windows distribution of training patterns that are transformed into time-frequency space. Because it is separated two algorithms that determines wavelet network structure and that modifies parameters of network, learning process that minimizes output error of network is executed after the network structure is determined. But this method has some weakness that training patterns must be transformed into time-frequency space by additional preprocessing and the network structure should be fixed during learning process. In this paper, we propose a new constructing method for wavelet network structure by using differences between the output and the desired response without preprocessing. Because the algorithm perform network construction and error minimizing process simultaneously, it can determine the number of hidden nodes adaptively as with the complexity of problems. In addition, the network structure is optimized by inserting new hidden nodes in the area that has maximum error and extracting hidden nodes that has no effect to the output of network. This algorithm has no constraint condition that all training patterns must be known, because it removes preprocessing procedure for training patterns and it can be applied effectively to systems that has time varying outputs.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.379-386
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• 2016

Purpose: The present study aims at researching the subjective satisfaction of patients who have experienced both conventional impression taking and digital impression taking to measure the possibility of wide clinical application of digital impression. Materials and methods: The study surveyed 170 adult patients over the age of 20, between October 2015 and April 2016, who voluntarily consented to participation and who experienced both conventional impression and digital impression at five dental hospitals that use intraoral digital impression. A total of 128 surveys were used for data analysis, involving frequency analysis, multiple response frequency analysis, descriptive statistics, and contingency table analysis, with the significance level set at 0.05. Results: Responses on the reason for taking impressions using the digital method appeared in the order of 'for implant treatment' (43.8%), 'for crown treatment' (30.5%), and 'for inlay treatment' (15.6%). Patients satisfaction was higher for digital impression taking than conventional impression taking (P<.05). As the preferred choice of impression, digital impression (60.2%) was higher than conventional impression (11.7%). Responses on the reason for choosing digital impression taking appeared in the order of 'no vomiting reflex' (35.1%), 'reliability of 3D digital scanning' (33.8%), and 'short time' (33.8%). Conclusion: The patients preferred digital impression taking to conventional impression taking in terms of satisfaction.

• Journal of Gastric Cancer
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• v.5 no.4 s.20
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• pp.260-265
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• 2005

Purpose: The protein kinase Chk1 is required for cell cycle arrest in response to DNA damage and is shown to play an important role in the G2/M checkpoint. The aim of this study was to investigate the relationship between microsatellite instability and frameshift mutation of the Chk1 gene in gastric cancers. Materials and Methods: The microsatellite instability was analyzed in 95 primary gastric carcinomas by using microdissection and 6 microsatellite markers. We also peformed single strand conformational polymorphism and sequencing to detect frameshift mutation of the Chk1 gene. Results: We found positive microsatellite instability in 19 (20%) of the 95 gastric cancers, 13 high- and 6 low-frequency microsatellite instability cases. The frameshift mutation of Chk1, which resulted in a truncated Chk1 protein, was detected in two high-frequency microsatellite instability cases. Conclusion: These data suggest that the microsatellite instability may contribute to the development of gastric carcinomas through inactivation of Chk1.

• Journal of Life Science
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• v.18 no.9
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• pp.1207-1211
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• 2008

The pro-inflammatory cytokine tumor necrosis factor-$\alpha$ (TNF-$\alpha$) is an important mediator of the immune response in hepatitis B virus (HBV) infection. Since the production of TNF-$\alpha$ is mostly regulated at the transcriptional level and polymorphisms in the TNF-$\alpha$ promoter alter its expression, TNF-$\alpha$ promoter polymorphisms could affect the pathogenesis of chronic HBV infection. In this study, we investigated the potential association of TNF-$\alpha$ promoter polymorphisms with chronic HBV infection. The study included 181 patients with chronic HBV infection, 201 persons who had been spontaneously recovered from hepatitis B, and 170 unrelated healthy controls. The -308G/A and -238G/A polymorphisms in the TNF-$\alpha$ promoter were analyzed by PCR-restriction fragment length polymorphism. The distribution of both the -308 and -238 genotypes in the patient group was not statistically different from that in the spontaneous recovery and control groups (p>0.05). There was also no significant difference in the allele frequency between the groups (p>0.05). The results suggest that the TNF-$\alpha$ -308 and -238 promoter polymorphisms are not associated with the development of chronic HBV infection in the Korean population.

• The Korean Journal of Food And Nutrition
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• v.29 no.1
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• pp.87-103
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• 2016

The purpose of this study was to analyze the food-related lifestyle choices of female baby boomers and to investigate variables regarding home meal replacement (HMR) buying behaviors and future needs. This study was conducted on 358 female baby boomers 53 years of age living in Gyeonggi and near Seoul. Out of 420 distributed questionnaires, 358 were returned and used for analysis (response rate: 85.2%). As a result of cluster analysis, three groups were identified based on the food-related lifestyles : a value-seeking group, a convenience-seeking group, and a health-seeking group. Among the three groups, there were significant differences in two socio-demographic characteristics, education level (p<0.05) and regular exercise (p<0.01), and in several health- and food-related habits, type of breakfast (p<0.01), type of dinner (p<0.05), dinner details (p<0.05), frequency of eating out (p<0.05), and eating habits score (p<0.01). The health-seeking group was significantly more likely to purchase ready to cook (RTC) items (59.1%) than were the other groups (p<0.001). However, the ratio of HMR purchasing for the purpose of meal replacement (p<0.05) and an HMR purchasing frequency of more than twice a week (p<0.001) were significantly lower in the health-seeking group. Reasons for selecting HMR showed a similar tendency among groups in taste (26.2%), convenience (18.7%), price (16.9%), safety (15.3%) and type of food (14.3%). However, the satisfaction scores for hygiene and safety reported by the health-seeking group were significantly lower than those reported by the other groups. More than two-thirds of all respondents were willing to purchase HMR in the future, though there were significant differences according to group: convenience-seeking group, 73.1%, health-seeking group, 70.1%, and value-seeking group, 65.7% (p<0.05). Our results suggest that the number of baby boomers purchasing HMR products will continue to grow and baby boomers will want HMR products to be more healthy (52.0%), safe (28.5%) and delicious (13.4%). An emphasis on taste was high in the convenience-seeking group, whereas an emphasis on health was high in the health-seeking and value-seeking groups. In conclusion, this study shows various food-related lifestyles amongst female baby boomers and illustrates the need to develop HMR marketing strategies targeted to these different lifestyles.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.17-23
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• 2017

Optical current sensors are suitable for operation in high voltage and high current environments such as power plants due to they are not affected by electromagnetic interference and have excellent insulation characteristics. However, as they operate in a harsh environment such as large temperature fluctuation and mechanical vibration, high reliability of the sensor is required. Therefore, many groups have been working on enhancing the reliability. In this work, an integrated optical current sensor incorporating polarization-rotated reflection interferometer is proposed. By integrating various optical components on a single chip, the sensor exhibits enhanced stability as well as the solution for low-cost optical sensors. Using this, we performed the characterization for the actual field application. By using a large power source, the current of 0.3 kA~36 kA was applied to the photosensor and the linear operation characteristics were observed. The error of the sensor was within $0{\pm}.5%$. Even when operating for a long time, the error range of the sensor was kept within $0{\pm}.5%$. In addition, the measurement of the frequency response over the range of 60 Hz to 10 kHz has confirmed that the 3-dB frequency band of the proposed OCT is well over 10 kHz.

• Korean Journal of Hospice Care
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• v.2 no.1
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• pp.41-57
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• 2002

This study was done to examine spiritual well-being of hospice care service volunteers for the purpose of providing them with programs promoting coping skills in response to the wholistic needs of patient effectively, also providing data for professional or nonprofessional hospice training program. Subjects were 123 volunteers serving in 6 hospice centers in Jeonbuk province at present. Data collection were done from 16 Oct. 2000 to 17 Nov. 2000. questionnairs were consisted of activities of hospice care service volunteer and spiritual well-being. The study results were as follows 1.Mean of activities of hospice care service volunteers were 2.433, those activities were divided into 5 categories such as spiritual, activities of volunteer for themselves, psychosocial, physical area and bereavement. The highest mean score was spiritual area 2.578, activities of volunteers for themselves 2.525, psychosocial area 2.456, physical area was 2.359 and the lowest mean score was bereavement area 2.130. 2.Spiritual well-being of hospice care service volunteers was 5.25, the highest mean. In subcategories of spiritual well-being, religious spiritual well-being was higher than existential spiritual well-being, mean score for each one was 5.41, 5.10. 3.Statistically significant relations among demographic characteristics such as gender(t=2.72, P=.008), status of marriage(t=6.067, P=.003), occupation(F=3.795, P=.025), frequency of visiting for volunteered hospice care(F=3.833, P=.024) were noted. 4.Statistically significant demographic characteristics of hospice service volunteers was religion(t=-4.38, p=0.000), status of marriage(F=3.505, p=0.033), frequency of visiting for volunteered hospice care(F=3.107, p=0.048), level of satisfaction from hospice care volunteer service(F=3.610, p=0.030), hospice service volunteers doing more home visiting(5-9times/month) had higher status of spiritual well being than volunteer with less home visiting(1-4times/month) 5.A significant relationship between activities of hospice service volunteers and status of spiritual well-being was noted(r=.236, p=.004), activities of hospice service volunteers was related to both subcategories of spiritual well-being such as religious well-being(r=.210, p=.010) and existential well-being(r=.208, p=.011). From the results of the study It is noted that status of spiritual well-being for hospice volunteers influences on service activities. It means spiritual well-being should be considered as a essential character for hospice service volunteers, it also means that managing and maintaining of status of spiritual well-being for hospice service volunteers is important. On the base of the study recommendation are made as follows: 1.Considering status of spiritual well-being for hospice care service volunteers is needed to promote hospice care activities. 2.It is necessary to develope spiritual well-being programs for hospice care service volunteers and further study for effect validation of them is needed. 3.Further study to sort out effecting variables for hospice care service volunteer activities is needed. 4.It will be desirable to have spiritual well-being information included in the hospice education program.