• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.10-21
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• 2015

Structural health monitoring (SHM) is a technique to diagnose an accurate and reliable condition of civil infrastructure by collecting and analyzing responses from distributed sensors. In recent years, aging civil structures have been increasing and they require further developed SHM technology for development of sustainable society. Wireless smart sensor and network technology, which is one of the recently emerging SHM techniques, enables more effective and economic SHM system in comparison to the existing wired systems. Researchers continue on development of the capability and extension of wireless smart sensors, and implement performance validation in various in-laboratory and outdoor full-scale experiments. This paper presents a summary of recent (mostly after 2010) researches on smart sensors, focused on the newly developed hardware, software, and validation examples of the developed smart sensors.

• KIEAE Journal
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• v.3 no.3
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• pp.43-50
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• 2003

Nowdays the apartment is a main type of modernized residential buildings. According to the improvement of construction techniques and functions of windows and doors, recent apartments are enhanced air tightness of windows, doors and building envelopes. As Infiltration is decreased and natural ventilation is reduced, energy could be saved in winter. However, indoor air quality is bad. The air Infiltration of a building could be enlarged by physical actions, such as building designs, constructions and reduction of air tightness which is caused by aging. This research analyzes and measures with KNS-4000P (Sapporo air tightness measurement) the air tightness of the high rise apartments which is recently constructed and not occupied yet. With depressurization method, the KNS-4000 installed on the window and the indoor air-leakage was measured. At that time, Air come out from the edge of the windows and doors because of the pressure differences between indoor and outdoor. We measure the amount of the air as effective air leakage areas. This method of depressurization takes less time to measure than other methods and is less affected from other conditions. We measured infiltration of total 56 household, 29 households S apartment (total floor area : $64.42m^2$) in Balan and 29 households D apartment(total floor area : $78.21m^2$) in Chonan. As a result of the field measurements at October 2003, normalized leakage area of D apartment in Cheonan was $2.05cm^2/m^2{\sim}3.49cm^2/m^2$ (average: $2.77cm^2/m^2$) and normalized leakage area of S apartment in Balan is $1.23cm^2/m^2{\sim}1.68cm^2/m^2$ (average: $1.5cm^2/m^2$).

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.55-59
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• 2014

Sarcopenia, or reduced muscle mass and volume, is due to various factors such as senile change, neuronal degeneration, drug, malignancy, and sepsis. Sarcopenia with the aging process has been evidenced by the decline in muscle mass by 0.5 to 1% per year with 3-5% reduction in muscle strength for 10 years between the ages of 40 and 50, and a 1-2% of decline of mass every year in people aged 60-70. Therefore, early diagnosis and understanding the mechanism of sarcopenia are crucial in the prevention of muscle loss. However, it is still difficult to image changes of muscle microstructure due to a lack of techniques. In this study, we developed an animal model using denervated rats to induce a rapid atrophy in the tibialis anterior (TA) and imaged its structural changes using optical coherence tomography (OCT) along with histologic and ultrasound analyses. Ultrasound showed changes of overall muscle size. Histology revealed that the atrophic TA muscle displayed an increased size variability of muscle fiber and inflammatory changes. Three dimensional OCT imaged the changes of perimysial grid and muscle fiber structure in real time without sacrifice. These observed advantages of multimodal imaging using OCT and ultrasound would provide clinical benefits in the diagnosis of sarcopenia.

• Journal of Digital Convergence
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• v.15 no.4
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• pp.191-198
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• 2017

It is needed to support intelligent customized health information service for user convenience in PHR based Personal Health Care Service Platform. In this paper, we specify an ontology-based health data model for Personal Health Care Service Platform. We also design a knowledge search algorithm that can be used to figure out similar health record by applying machine learning and data mining techniques. Axis-based mining algorithm, which we proposed, can be performed based on axis-attributes in order to improve relevance of knowledge exploration and to provide efficient search time by reducing the size of candidate item set. And K-Nearest Neighbor algorithm is used to perform to do grouping users byaccording to the similarity of the user profile. These algorithms improves the efficiency of customized information exploration according to the user 's disease and health condition. It can be useful to apply the proposed algorithm to a process of inference in the Personal Health Care Service Platform and makes it possible to recommend customized health information to the user. It is useful for people to manage smart health care in aging society.

• Journal of Surface Science and Engineering
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• v.29 no.5
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• pp.345-349
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• 1996

The wetting property of polymer surfaces is very important for practical applications. Plasma source ion implantation technique was used to improve the wetting properties of polymer surfaces. Poly(ethylene terephtalate) and other polymer sheets were mounted on the target stage and an RF plasma was generated by means of an antenna located inside the vacuum chamber. High voltage pulses of up to -10kV, 10 $\mu$sec, and up to 1 kHz were applied to the stage. The samples were implanted for 5 minutes with using Ar, $N_2,O_2,CH_4,CF_4$ and their mixture as source gases. A contact angle meter was used to measure the water contact angles of the implanted samples and of the samples stored in ambient conditions after implantation. The modified surfaces were analysed with Time-Of-Flight Mass Spectrometer (TOF-SIMS) and Auger Electron Spectroscopy (AES). The oxygen-implanted samples showed extremely low water contact angles of $3^{\circ}C$ compared to $79^{\circ}C$ of unimplanted ones. Furthermore, the modified surfaces were relatively stable with respect to aging in ambient conditions, which is one of the major concerns of the other surface treatment techniques. From TOF-SIMS analysis it was found that oxygen-containing functional groups had been formed on the implanted surfaces. On the other hand, the $CF_4$-implanted samples turned out to be more hydro-phobic than unimplanted ones, giving water contact angles exceeding $100^{\circ}C$ . The experiment showed that plasma source ion implantation is a very promising technique for polymer surface modification especially for large area treatment.

• Toxicological Research
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• v.28 no.4
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• pp.241-248
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• 2012

Exposure of cells to ultraviolet B (UVB) radiation can induce production of free radicals and reactive oxygen species (ROS), which damage cellular components. In addition, these agents can stimulate the expression of matrix metalloproteinase (MMP) and decrease collagen synthesis in human skin cells. In this study, we examined the anti-photoaging effects of extracts of Tetraselmis suecica (W-TS). W-TS showed the strongest scavenging activity against 2,2-difenyl-1-picrylhydrazyl (DPPH) and peroxyl radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. We observed that the levels of both intracellular ROS and lipid peroxidation significantly increased in UVB-irradiated human skin fibroblast cells. Furthermore, the activities of enzymatic antioxidants (e.g., superoxide dismutase) and the levels of non-enzymatic antioxidants (e.g., glutathione) significantly decreased in cells. However, W-TS pretreatment, at the maximum tested concentration, significantly decreased intracellular ROS and malondialdehyde (MDA) levels, and increased superoxide dismutase and glutathione levels in the cells. At this same concentration, W-TS did not show cytotoxicity. Type 1 procollagen and MMP-1 released were quantified using RT-PCR techniques. The results showed that W-TS protected type 1 procollagen against UVB-induced depletion in fibroblast cells in a dose-dependent manner via inhibition of UVB-induced MMP-1. Taken together, the results of the study suggest that W-TS effectively inhibits UVB-induced photoaging in skin fibroblasts by its strong anti-oxidant ability.

• Smart Structures and Systems
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• v.7 no.4
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• pp.241-262
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• 2011

Cast iron pipe has been used as a water distribution technology in North America since the early nineteenth century. The first cast iron pipes were made of grey cast iron which was succeeded by ductile iron as a pipe material in the 1940s. These different iron alloys have significantly different microstructures which give rise to distinct mechanical properties. Insight into the non-destructive structural condition assessment of aging pipes can be advantageous in developing mitigation strategies for pipe failures. This paper examines the relationship between the small-strain and large-strain properties of exhumed cast iron water pipes. Nondestructive and destructive testing programs were performed on eight pipes varying in age from 40 to 130 years. The experimental program included microstructure evaluation and ultrasonic, tensile, and flexural testing. New applications of frequency domain analysis techniques including Fourier and wavelet transforms of ultrasonic pulse velocity measurements are presented. A low correlation between wave propagation and large-strain measurements was observed. However, the wave velocities were consistently different between ductile and grey cast iron pipes (14% to 18% difference); the ductile iron pipes showed the smaller variation in wave velocities. Thus, the variation of elastic properties for ductile iron was not enough to define a linear correlation because all the measurements were practically concentrated in single cluster of points. The cross-sectional areas of the specimens tested varied as a result of minor manufacturing defects and levels of corrosion. These variations affect the large strain testing results; but, surface defects have limited effect on wave velocities and may also contribute to the low correlations observed. Lamb waves are typically not considered in the evaluation of ultrasonic pulse velocity. However, Lamb waves were found to contribute significantly to the frequency content of the ultrasonic signals possibly resulting in the poor correlations observed. Therefore, correlations between wave velocities and large strain properties obtained using specimens manufactured in the laboratory must be used with caution in the condition assessment of aged water pipes especially for grey cast iron pipes.

• International Journal of Advanced Culture Technology
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• v.6 no.4
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• pp.323-330
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• 2018

The growth of the older population is expected to further increase social problems associated with population aging, such as isolation, poverty, and depression. The emerging issues associated with the older population are also expected to provide further momentum on studies about the dwelling environment as factors that ensure the health of older people as well as improve their quality of life. Therefore, approaches for explaining the issues of the older age group should be diversified using a variety of factors and appropriate analytic tools. Studies on measuring depression have principally focused on assessing an objective self-report questionnaire, usually in a highly structured, textual form which may not reflect the cognitive impairment of older adults. The aim of this study was to define and measure dwelling depression among older adults in Korea. There are two specific hypotheses in this study as follows: (a) there will be statistically significant relationships with dwelling dissatisfaction and depression, and (b) dwelling depression tools containing text and images will be, respectively, assessment tools that have a good construct with content validity and reliability. In the first experiment, to define and measure dwelling depression, 301 people over 65 years old living in single and two-person households were surveyed using a text-based dwelling depression questionnaires from September 1-30, 2017. In the second experiment, to examine whether the projective image questionnaire could serve as a suitable replacement for the text-based questionnaires, the same participants were surveyed from January 22 to February 2, 2018. The results show that depression has a close correlation with dwelling dissatisfaction. In addition, the geriatric dwelling depression index (GDDI) based on the projective image was refined. Additionally, the projective image questionnaire has a close correlation with the text-based questionnaire. Finally, through ROC curve analysis, it was found that the projective image questionnaire can accurately predict a depression group. To this end, this preliminary study examined the validity of the projective image questionnaire in older adults to make this instrument feasible for older populations and to contribute to a profound understanding of geriatric depression due to the living environment. We hope they will provide a basis for further research on psychological diagnoses using projective images.

• Smart Structures and Systems
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• v.24 no.5
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• pp.669-681
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• 2019

Bridge collapses may deliver a huge impact on our society in a very negative way. Out of many reasons why bridges collapse, poor maintenance is becoming a main contributing factor to many recent collapses. Furthermore, the aging of bridges is able to make the situation much worse. In order to prevent this unwanted event, it is indispensable to conduct continuous bridge monitoring and timely maintenance. Visual inspection is the most widely used method, but it is heavily dependent on the experience of the inspectors. It is also time-consuming, labor-intensive, costly, disruptive, and even unsafe for the inspectors. In order to address its limitations, in recent years increasing interests have been paid to the use of unmanned aerial vehicles (UAVs), which is expected to make the inspection process safer, faster and more cost-effective. In addition, it can cover the area where it is too hard to reach by inspectors. However, this strategy is still in a primitive stage because there are many things to be addressed for real implementation. In this paper, a typical procedure of bridge inspection using UAVs consisting of three phases (i.e., pre-inspection, inspection, and post-inspection phases) and the detailed tasks by phase are described. Also, three major challenges, which are related to a UAV's flight, image data acquisition, and damage identification, respectively, are identified from a practical perspective (e.g., localization of a UAV under the bridge, high-quality image capture, etc.) and their possible solutions are discussed by examining recently developed or currently developing techniques such as the graph-based localization algorithm, and the image quality assessment and enhancement strategy. In particular, deep learning based algorithms such as R-CNN and Mask R-CNN for classifying, localizing and quantifying several damage types (e.g., cracks, corrosion, spalling, efflorescence, etc.) in an automatic manner are discussed. This strategy is based on a huge amount of image data obtained from unmanned inspection equipment consisting of the UAV and imaging devices (vision and IR cameras).

• Journal of dental hygiene science
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• v.21 no.1
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• pp.70-78
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• 2021

Background: The aim of this study was to analyze the public demand for information about the job of dental hygienists by mining text data collected from the online Q & A section on an Internet portal site. Methods: Text data were collected from inquiries that were posted on the Naver Q & A section from January 2003 to July 2020 using "dental hygienist job recognition," "role recognition," "medical assistance," and "scaling" as search keywords. Text mining techniques were used to identify significant Korean words and their frequency of occurrence. In addition, the association between words was analyzed. Results: A total of 10,753 Korean words related to the job of dental hygienists were extracted from the text data. "Chi-lyo (treatment)," "chigwa (dental clinic)," "ske-illing (scaling)," "itmom (gum)," and "chia (tooth)" were the five most frequently used words. The words were classified into the following areas of job of the dental hygienist: periodontal disease treatment and prevention, medical assistance, patient care and consultation, and others. Among these areas, the number of words related to medical assistance was the largest, with sixty-six association rules found between the words, and "chi-lyo," "chigwa," and "ske-illing" as core words. Conclusion: The public demand for information about the job of dental hygienists was mainly related to "chi-lyo," "chigwa," and "ske-illing" as core words, demonstrating that scaling is recognized by the public as the job of a dental hygienist. However, the high demand for information related to treatment and medical assistance in the context of dental hygienists indicates that the job of dental hygienists is recognized by the public as being more focused on medical assistance than preventive dental care that are provided with job autonomy.