• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.791-795
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• 2016

The effects of $TiO_2$ addition on the electrical insulation of AlN ceramics with 1 wt% $Y_2O_3$ as a sintering aid have been investigated. Some of $TiO_2$ has reacted with AlN powders and transformed to fine TiN particles during sintering, which was uniformly dispersed along grain boundaries of AlN. At a high electrical field (500 V/mm), the resistivity of AlN ceramics with $TiO_2$ addition of 0.2 wt% increased about 1000 times from $3{\times}10^{10}{\Omega}cm$ to $3.1{\times}10^{13}{\Omega}cm$. Based on the impedance spectroscopy measurement, it was found that $TiO_2$ addition increased dramatically electrical resistivity of AlN grains much more than that of grain boundaries. Thus, $TiO_2$ was believed to dissolve inside AlN grains to suppress ionic conduction of Al vacancies. This suppressed ionic conduction by Ti incorporation into AlN grains seems to contribute to more electrically insulating AlN ceramics.

• Proceedings of the ESK Conference
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• 1993.04a
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• pp.100-109
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• 1993

To investigate the work-relatedness of carpal tunnel syndrome of some workers at packing department in a rayon manufacturing company, reseracher studied the symptoms and physical sign related to carpal tunnel syndrome of the workers at packing, ysrning, and washing department. The results are as follows: 1. By the results of ergonomic study, the packing work had the considerable probability to develop the carpal tunnel syndrome. 2. The prevalences of symptoms, physical sign and case by definition were higher in woman workers than in man workers. 3. In female workers, the age-agjusted prevalence rates of symptoms were 11.6/1, 000 in workers at washing department, 111.6/1, 000 in workers at packing department, and 70.1/1, 000 in workers at yarning department. In male workers, the age- adjusted rates of symptoms were 92.1/1, 000 in workers at washing department, 210.1/1, 000 in workers at packing and delivery department, and 0.0/1, 000 in workers at yarning department. 4. In female workers, the age-adjusted prevalence rates of physical signs were 119.5/1, 000 in workers at washing department, 104.4/1, 000 in workers at packing department, and 84.5 in workers at yarning department. In male workers, the age-adjusted rates of physical signs were 65.7/1, 000 in workers at washing department, 59.0/1, 000 in workers at packing and delivery department, and 176.9/1, 000 in workers at yarning department. 5. In female workers, the age- adjusted prevelence rates of carpal tunnel cases by case definition were 123.1/1, 000 in workers at washing department, 1117.2/1, 000 in workers at packing department, and 60.2/1, 000 in workers at yarning department. In male workers, the age-adjusted of cases were 355.9/1, 000 in workers at packing and delivery department, and 0.0/1, 000 in workers at other two departments. 6. The most of female workdrs at washing departmentn had the work history at packing department. 7. We concluded the carpal tunnel syndrome of female workers at packing department were work related.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.2
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• pp.112-125
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• 2015

Making a model that is an accurate replica of the oral structure requires precision and efficiency. Nowadays, rapid technological advances bring digitalization in dentistry. One of the most important works in digital dentistry is three-dimensional modeling of the oral cavity and digitizing the 3D data. Among the three components of CAD/CAM, (1) data capture component (digitizers), (2) design component (CAD software), (3) manufacturing component (CAM), the basic component that has a significant impact on the other processes is the data capture component, i.e. intra-oral scanners. This literature review discusses the principles and clinical use of intra-oral scanners in dentistry based on recent publications of the past 5 years using the PubMed and Google Scholar databases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3C
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• pp.255-263
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• 2010

In this paper, we present an efficient cooperative transmission scheme for high speed 60GHz WPAN system. In 60GHz, the cooperative transmission with relay is effective scheme because signals are exceedingly attenuated according to the distance and the transmission is impossible when there is no LOS between transmitter and receiver. Moreover, the reliability of signal in destination can be improved by receiving data from a relay as well as a transmitter. However, the overall data rate is reduced because transmission time is more required for relay. To solve this problem, we propose a cooperative transmission scheme with RS-CC serial concatenated codes. In the proposed cooperative transmission scheme, the relay can reduce the transmission data size because the only parity bits of systematic RS code are transmitted after encoding by CC. But the computational complexity is increased at the relay and the destination.

• Journal of Biomedical Engineering Research
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• v.19 no.2
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• pp.113-118
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• 1998

By their rapid and periodic actions, the cilia of the human respiratory tract play an important role in clearing inhaled noxious particles. Based on the automated image-processing technique, we studied the method analyzing ciliary beat frequency (CBF) objectively and quantitatively. Microscopic ciliary images were transformed into digitized gray ones through an image-grabber, and from these we extracted signals for CBF. By means of a FFT, maximum peak frequencies were detected as CBFs in each partitioned block for the entire digitized field. With these CBFs, we composed distribution maps visually showing the spatial distribution of CBFs. Through distribution maps of CBF, the whole aspects of CBF changes for cells and the difference of CBF of neighboring cells can be easily measured and detected. Histogram statistics calculated from the user-defined polygonal window can show the local dominant frequency presumed to be the CBF of a cell or a crust the region includes.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.339-344
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• 2000

The mucociliary system is one of the most important airway defense mechanisms in human body and impairment of ciliary movement results in various diseases in respiratory tract. In this study, we have developed a system that can measure ciliary movement in vivo and quantified ciliary beat frequency (CBF) through autoregressive (AR) power spectrum. To measure the frequency in vivo, we applied a photoelectric method that was composed of a laser light and a fiber optic probe. Scattered signals are transferred to a PC in which they are displayed on the monitor and its CBF is determined by the AR method in were acquired. For 8 normal subjects, the analyzed CBFs ranged from 5 to 10Hz and its mean was 7.3${\pm}$1.1Hz. This result showed similar aspects to the reported results of CBFs to data. We expect that this result will be applied in various clinical studies such as analysis of CBF changes by drugs or by diseaes.

• Korean Journal of Social Welfare Studies
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• v.40 no.3
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• pp.99-124
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• 2009

This study investigates the problems of welfare decentralization reform implemented by Roh Mu-Hyun Administration and examines a policy direction for improving the decentralization. The reform has caused various problems. Local governments have suffered from heavy financial burden. Some social services, devolved into local governments, have not adequately provided as before. In addition, fiscal disparity among localities has increased. To deal with these problems, experts have proposed several plans, such as restoring the devolved programs to national subsidy programs, inventing a new social welfare grant, or introducing block grants. This study suggests that some of the devolved welfare programs should be restored to the national subsidies, since they cannot be maintained properly by local governments. Also, we need to adjust financial responsibilities between the central and local government in the national subsidy programs. Introducing block grant can be one satisfying solution to enhance local autonomy while maintaining the financial responsibility of central government. In some national subsidy programs, the financial contribution by the central government should be increased to alleviate financial burden of local governments.

• Korean Journal of Remote Sensing
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• v.37 no.6_3
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• pp.1923-1929
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• 2021

Earth observation satellites are being used in various field and are being developed in many countries due to their high utility and marketability. Korea is developing various Earth observation satellites according to National Space Development Plan. Among them, the Korea Multi-Purpose Satellite(KOMPSAT) series is the most representative low-orbit satellite. So far, a total of five KOMPSAT have been launched to meet the national image demand and have been used in various fields, including national institutions. This special issue introduces research related to data processing, analysis, and utilization using various image data from the KOMPSAT series. Meanwhile, for the uninterrupted utilization of the subsequent KOMPSAT image data, data processing and utilization research suitable for high-resolution images must be continued, and related research contents will be continuously shared through a special issue.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.4
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• pp.510-520
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• 2021

Objective: This paper aimed to provide estimates the burden of cancer attributable to occupational exposures in South Korea and to review the processes of estimating the population attributable fraction(PAF). Methods: The PAFs of occupational cancer were reviewed from previous studies. The number and proportion of cancer cases attributable to occupational carcinogens were estimated by multiplying the PAFs by recent Korean cancer data(up to 2016 for incidence and 2017 for death) obtained from the Statistics Korea. The estimation of PAFs included occupational exposures defined as definite or probable human carcinogens by the International Agency for Research on Cancer. Results: In South Korea, an estimated 10,769 new cancer cases(9,017 among men, 1,752 among women) in 2016, and 7,030 cases of death from cancer(6,047 in men, 983 in women) in 2017, were attributable to occupational exposures, representing 1.5-4.7% of all new cancer cases(2.1-7.5% and 0.3-1.6% among men and women, respectively) and 2.7-8.9% of all cancer death cases(3.4-12.4% and 0.5-3.3% among men and women, respectively). Among men and women, lung cancer was the most impactful. The estimation process of PAFs, however, has a variety of uncertainties. Conclusions: Occupational exposures contribute to a substantial burden of cancer in South Korea. PAFs for cancer provide useful information for prevention initiatives and prioritizing health policies for workers. However, PAFs need to be interpreted cautiously and updated regularly.

• Korean Journal of Remote Sensing
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• v.34 no.6_4
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• pp.1469-1478
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• 2018

Earthquakes and volcanic eruptions are disaster that causes billions of dollars in property damage and the loss of human life. Therefore, it is required to effectively monitor earthquakes and volcanoes. With the increase of satellite data, researches on earthquake and volcano using satellite imagery has been improved. Satellite images can be divided into three types i.e. optical, thermal, Synthetic Aperture Radar (SAR) and each image has different characteristics. In this article, we summarized its advantages and disadvantages of each type of satellite image. Moreover, we investigated the previous researches about earthquake and volcano using satellite images. Finally, we suggest application method to respond earthquake and volcano disaster using satellite images.