• Proceedings of the Korean Society of Rheology Conference
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• 2006.06a
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• pp.61-64
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• 2006

Soft materials, such as polymer solutions, gels and filamentous protein materials in cells, show complicated behavior due to their complex structures and dynamics with multiple characteristic time and length scales. Several complementary techniques have been developed to measure viscoelastic of soft materials. Especially, particle tracking microrheology, using the Brownian motion of particles in a medium to get rheological properties, has recently been improved both theoretically and experimentally. Compared to other conventional methods, video particle tracking microrheology has some advantages such as small sample volume, detecting spatial variation of local rheological properties, and less damage to sample materials. With these advantages, microrheology is more suitable to measure the properties of complex materials than other mechanical rheometries.

• Journal of Korean society of Dental Hygiene
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• v.21 no.5
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• pp.595-600
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• 2021

Objectives: For postmenopausal women who participated in the 2019 National Health and Nutrition Examination Survey, we aimed to provide basic data for oral health management interventions and oral policies for each life cycle of postmenopausal women by identifying the relationship between physical activity and depression on oral health behavior and awareness symptoms. Methods: The participants of this study were 1,628 menopausal women, and their general characteristics, physical activity, depression, and oral health behavior and awareness symptoms were investigated. This study used the complex sample frequency analysis, complex sample 𝞆² test, and logistic regression analysis method, which is a sample design of the National Health and Nutrition Examination Survey. Results: The factors influencing physical activity were the use of oral hygiene device and chewing difficulty. and the influencing factors of depression experience were pain and chewing difficulty. Conclusions: As a result, physical activity and depression experience should be utilized by developing and oral health program for the promotion of oral health in postmenopausal women.

• Korean Journal of Materials Research
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• v.34 no.2
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• pp.105-110
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• 2024

Scanning probe microscopy (SPM) has become an indispensable tool in efforts to develop the next generation of nanoelectronic devices, given its achievable nanometer spatial resolution and highly versatile ability to measure a variety of properties. Recently a new scanning probe microscope was developed to overcome the tip degradation problem of the classic SPM. The main advantage of this new method, called Reverse tip sample (RTS) SPM, is that a single tip can be replaced by a chip containing hundreds to thousands of tips. Generally for use in RTS SPM, pyramid-shaped diamond tips are made by molding on a silicon substrate. Combining RTS SPM with Scanning spreading resistance microscopy (SSRM) using the diamond tip offers the potential to perform 3D profiling of semiconductor materials. However, damage frequently occurs to the completed tips because of the complex manufacturing process. In this work, we design, fabricate, and evaluate an RTS tip chip prototype to simplify the complex manufacturing process, prevent tip damage, and shorten manufacturing time.

• Journal of Integrative Natural Science
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• v.5 no.4
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• pp.241-245
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• 2012

Categorical data collected based on complex sample design is not proper for the standard Pearson multinomial-based chi-squared test because the observations are not independent and identically distributed. This study investigates effects of bias of point estimator of population proportion and its variance estimator to the standard Pearson chi-squared test statistics when the sample is collected based on complex sampling scheme. This study examines the effect under two population homogeneity test. The standard Pearson test statistic can be partitioned into two parts; the first part is the weighted sum of ${\chi}^2_1$ with eigenvalues of design matrix as their weights, and the additional second part which is added due to the biases of the point estimator and its variance estimator. Our empirical analysis shows that even though the bias of point estimator is small, Pearson test statistic is very much inflated due to underestimate the variance of point estimator. In the connection of design-based variance estimator and its design matrix, the bigger the average of eigenvalues of design matrix is, the larger relative size of which the first component part to Pearson test statistic is taking.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.3
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• pp.207-214
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• 1997

We collected airborne complex mixtures in a industrial area of Yeochun, and examined whether these complex mixtures could affect gap junctional intercellular communication (GJIC) in a cultured WBF-344 rat liver epithelial cells (LEC). Since the reduction of GJIC plays an important role in chemical carcinogenesis, measurement of changes of GJIC is a meaningful method to screen carcinogenicity of these mixtures. High and low volume samples were dissolved in dimethyl sulfoxide (DMSO) and tested. Blank filter extractions were also examined for exclud-ing possible toxicity of filter itself, and TPA (12-O-tetradecanoylphorbol-13-acetate) and DMSO were used as positive and negative control, respectively. When the cells were exposed to samples at concentration below that required to maintain rather than 85% cell viability based on the result of neutral red uptake assay, maximal inhibition of GJIC was observed at 1hr after treatment with both high and low volume samples by scrape-loading dye transfer assay. In fluorescence recovery after photobleaching assay, recovery rates via gap junctions were 33%/min in high volume sample and 62%/min in low volume sample. In together, airborne samples collected in Yeochun inhibited GJIC in a cultured WBF-344 rat LEC. These results suggest airborne samples tested in this experiment may attribute to cause a certain type and degree of cancers in in vivo when exposured for some periods.

• Journal of the Korean Society of Food Culture
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• v.32 no.3
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• pp.235-243
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• 2017

We investigated the antioxidant, physicochemical, and sensory characteristics of dried type sodium-reduced Bibimbap using dandelion complex powder (DCP). DCP is known to add moisture to the skin and relieve symptoms of atopic dermatitis. The sodium content of the standard sample was 1,110.87 mg per serving. The sodium was significantly reduced by 30%, resulting in 762.62 mg of sodium for the reduced sodium group (p<0.05). The ash contents of the standard sample group with DCP showed the highest value (3.17%) in all samples and was affected by minerals of DCP (p<0.05). The total flavonoid contents and ABTS radical scavenging activity, indicators of antioxidant, anticancer and antibacterial activities, showed significantly high activities with addition of DCP (p<0.05). In the sensory results, bulgogi and savory flavor of the samples with DCP showed significantly higher values, and samples with DCP received the highest scores for after-taste. All samples were confirmed to be microbiologically safe according to the food code applied to food manufacturers. Pathogenic microorganisms tests were either negative or not detected in all samples.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.95-96
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• 2006

As the power industry moves towards open competition, there has been a call for methodology to evaluate distribution power system reliability by using customer interruption costs. Accordingly, it is increased for methodology to evaluate distribution power system reliability in power supply zones under competitive electricity market. This paper presents algorithm to evaluate system average interruption duration index. expected energy not supplied and system outage cost taking Into consideration failure rate of distribution facility and industrial customer interruption cost. Also, to apply this algorithm to evaluate system outage cost presented in this paper, distribution system of a dual supply system consisting of mostly high voltage customers in industrial complex in Korea is used as a sample case study. Finally, evaluation results of system interruption cost, system average interruption duration index and expected energy not supplied in sample industrial complex area are shown in detail.

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.166-171
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• 2010

In this paper, the front-end of a digital receiver with a 25 kHz carrier frequency, 5 kHz symbol rate, and any excess-bandwidth is designed using two basic facts. The first is known as the uniform sampling theorem, which states that the sampled sequence might not suffer from aliasing even if its sampling rate is lower than the Nyquist sampling rate if the analog signal is a bandpass one. The other fact is that if the sampling rate is 4 times the center frequency of the sampled sequence, the front-end processing complexity can be dramatically reduced due to the half of the sampled sequence to be multiplied by zero in the demixing process. Furthermore, the designed front-end is simplified by introducing sub-filters and sub-sampling sequences. The designed front-end is composed of an A/D converter, which takes samples of a bandpass filtered signal at a 20 kHz rate; a serial-to-parallel converter, which converts a sampled bandpass sequence to 4 parallel sub-sample sequences; 4 sub-filter blocks, which act as a frequency shifter and lowpass filter for a complex sequence; 4 synchronized switches; and 2 adders. The designed front-end dramatically reduces the computational complexity by more than 50% for frequency shifting and lowpass filtering operations since a conventional front-end requires a frequency shifting and two lowpass filtering operations to get one lowpass complex sample, while the proposed front-end requires only four filtering operation to get four lowpass complex samples, which is equivalent to one filtering operation for one sample.

• Korean journal of food and cookery science
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• v.33 no.3
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• pp.264-274
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• 2017

Purpose: The purpose of this study was to analyze the meal types by cooking methods provided at different meal provision places using the 2015 Korea National Health and Nutrition Examination Survey. Methods: A total of 42,441 meal data on adults from the 2015 Korea National Health and Nutrition Examination Survey were used for analysis. The data were analyzed by complex sample $x^2-test$ of independence and complex sample logistic regression analysis using SPSS 23.0 for Windows. Results: The meal provision place showing the highest frequency was home (60.2%), followed by commercial (32.5%) and institutional foodservices (7.3%). The meal types by cooking method most frequently consumed were rices (18.3%) and kimchis (16.6%). The results of the complex sample logistic regression analysis showed that breads & snacks, steamed or braised dishes, fried dishes, and fresh seasoned vegetables were more likely to be consumed at commercial or institutional foodservices than at home. In addition, noodles & dumplings were more likely to be consumed at commercial places, and Korean soups were consumed at institutional foodservices. Conclusion: From the results of this study, it is suggested to develop recipes for substitution of fried dishes and to develop low sodium recipes at commercial and institutional foodservices. In addition, education of consumers of commercial foodservice is needed to reduce consumption of fried dishes, salted seafoods, and pickled vegetables and encourage consumers to choose meals from institutional foodservice managed by dietitians.

• Journal of Korean society of Dental Hygiene
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• v.21 no.6
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• pp.763-771
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• 2021

Objectives: The purpose of this study was to examine the association between periodontitis and health behavior in women aged ≥40 years. In addition, related factors were compared according to the presence or absence of cardiovascular disease. Methods: Data from the 7th Korean National Health and Nutrition Examination Survey (2016-2018) were used. The study included 3,801 women aged 40-79 years, who participated in a questionnaire health survey related to hypertension, stroke, myocardial infarction, and angina pectoris, as well as completed blood tests, anthropometry, and oral examination. Statistical analyses were performed using complex sample general linear, complex sample crosstabs, and complex sample logistic regression analyses. Results: In all subjects, smoking and drinking, use of interdental care products, and dental checkups were confirmed to be significantly related to periodontitis. In the group with cardiovascular disease, the use of interdental care products, experience in dental checkups, and toothbrushing more than three times a day were confirmed as significant factors for lowering the prevalence of periodontitis. In the group without cardiovascular disease, smoking and drinking, use of interdental care products, and experience in dental checkups were confirmed as the significant factors. Conclusions: To improve the periodontal health of women over 40 years of age with cardiovascular disease, a health education program including self-care methods for proper dental plaque management and regular dental checkups are critical. Additionally, awareness of the risks of smoking and drinking would be helpful even for women without cardiovascular diseases.