• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.543-550
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• 2018

The rapid growth of IoT technology induced by the fourth industrial revolution has resulted in research into various types of wireless sensors, and applications based on this technology are prevalent in many areas. However, among the various sites where this technology is used, railway bridges and tunnels with lengths of tens of kilometers have problems with data acquisition, due to the signal noise induced by the long distance measurement and EMI induced by the high voltage power feeding system, when conventional electric sensors are used. To overcome these problems, many studies on fiber optic sensors have been conducted as a substitute for the conventional electric sensors. However, restrictions on the types of fiber optic sensors have limited their application in railways. For this reason, a hybrid measurement system with IoT based wireless data communication, in which both electric and fiber optic sensors can be applied simultaneously, has been developed. In this study, in order to evaluate the applicability of the hybrid measurement system developed in the previous study, a real-time test for 4 types of measurement environments, which reflect possible railway sites, is performed. As a result, it was confirmed that the signals from both the electric and fiber optic sensors, which were acquired at a remote area in real-time, showed good agreement with each other and that this measurement system has the potential to handle sensors with a sampling rate of 2.5 kHz. In the future, it is expected that the IoT-based hybrid measurement system will contribute to the improvement of structural safety by enabling real-time structural health monitoring when applied to various measurement sites.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.282-293
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• 2020

This study investigated a long-term variation trend of water quality, fish compositions, and ecological health conditions in the Gwanpyeong stream located in the nearby Daejeon metropolitan city to understand the impact of urban development projects on the aquatic ecosystem. The sampling was made in four surveys (2009, 2010, 2016, 2019) before and after urbanization. The urban development was conducted in 2008, resulting in the stream's ecological disturbance, and the stream restoration was conducted in 2012. Thus, stream monitoring was conducted to analyze the ecological trends before and after the restoration. The multi-metric models for Fish Assessment Index(FAI) and necropsy-based Health Assessment Index(HAI) were applied in the fish community and organ-level, respectively, to assess the ecological health of the stream. Minimum turbidity and chlorophyll-a(Chl-a) occurred in the mid-stream(St. 2), and this was probably due to rapid current velocity in the riffle zone. We collected 18 fish species, and the dominant species was Zacco platypus (40.6%). In 2016 immediately after the stream restoration, the relative proportions of sensitive species and insectivore species were the highest along with highest values in the species diversity and species richness index, resulting in the best condition in the ecological health, based on FAI model values. However, the ecological health, based on the FAI, became worse in the latest survey conducted in 2019. The analysis of the HAI model based on the organ-level approach showed skin erosion in the fish of upper stream, kidney defects in downstream, and the liver and gill defects observed in all sites, indicating that the anatomical health was also affected.

• Journal of Environmental Health Sciences
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• v.33 no.5
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• pp.408-421
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• 2007

The concentration characteristics of atmospheric particle matters (PM) including $PM_{2.5},\;PM_{10}$, and TSP were evaluated through the measurement data of PM_{2.5}$ (fine particulate), PM_{10-2.5}$ (coarse particulate), and PM_{over-10}$ collected using a MCI (multi-nozzle cascade impactor) sampler of a three-stage filter pack in spring of 2006 in Iksan area. During the sampling period of 10-15 March and 24 days from 8 April to 2 May, 32 samples for PM of each size fractions were collected, and then measured for PM mass concentrations and water-soluble inorganic ion species. Average concentrations of $PM_{2.5},\;PM_{10}$, TSP were $57.9{\pm}44.1mg/m^3$, $96.6{\pm}89.1mg/m^3$, and $114.8{\pm}99.7mg/m^3$, respectively. Water-soluble inorganic ion fractions to PM mass were found to be 36.5%, 18.0%, and 11.1% for $PM_{2.5}$, $PM_{10-2.5}$ and $PM_{over-10}$, respectively. By showing the high concentrations of PM samples during Asian dust events, those three fractions of PM were distinguished between the samples of Asian dust event and the samples of no event. However, the increase of PM concentrations observed during Asian dust events showed a different pattern for some Asian dust events. The differences of those three fractions in the size distribution may depend on differences on place of occurrence of Asian dust storm and course of transport from China continent to Iksan area in Korea. However, the extent of PM mass contribution during Asian dust events was generally dominated by the coarse particles rather than the fine fraction of PM. The variations of water-soluble inorganic ion species concentration in those three PM fractions between the samples of Asian dust event and the samples of no event were also discussed in this study.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.4
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• pp.402-411
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• 2013

Objectives: This study aims to assess the concentrations of ammonia and hydrogen sulfide according to task unit area at swine farms. Methods: A total of six swine farms were selected for this study. Ammonia and hydrogen sulfide were monitored using a real-time multi-gas monitor which could sample the gases simultaneously. The sampling was done in the pig building, manure storage facility and composting facility of each farm. Results: The concentration of ammonia in the pig buildings(GM 22.6 ppm, GSD 2.3) was significantly higher(p<0.0001) than in the manure storage facilities(GM 10.4 ppm, GSD 2.7) and composting facilities(GM 8.6 ppm, GSD 2.8). The concentration of hydrogen sulfide in the manure storage facilities(GM 9.8 ppm, GSD 3.2) was higher(p<0.0001) than in the pig buildings(GM 2.3 ppm, GSD 2.3) and composting facilities(GM 1.9 ppm, GSD 2.5). In particular, the levels of hydrogen sulfide in the confined manure storage facilities were higher than those in open-type facilities and the peak concentration(98 ppm) in the confined facilities was approximate to 100 ppm, at the value of Immediately Dangerous to Life or Health(IDLH). Conclusions: Suffocation accidents caused by hazardous gases at a swine farm have occurred annually. Real-time monitoring of the hazards should be done in order to protect farm workers and livestock from the sudden accidents.

• Journal of Korean Home Economics Education Association
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• v.16 no.3
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• pp.115-129
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• 2004

We investigated the prevalence of eating disorder risk group and its relationship with Physique status and eating behavior among high school students in Daejeon. In May - June 2002, 350 students were sampled from 6 high schools in Daejeon by multi-stage cluster sampling and assessed with self-completing questionnaires. We used the Korean version of Eating Attitude test(EAT-26) to screen eating disorder risk group. and other instruments to screen physique status and eating behavior. The response rate was 91%(total 320) and numbers of female students were 167(52.2%) and male students were 153(47.8%). Average age was 16.0${\pm}$0.35 years, and average body-mass index(BMI) and PIBW(Percent Ideal Body Weight) were 20.9${\pm}$3.3 Kg/m2 and 102${\pm}$4.2% in male students, 20.2${\pm}$3.7 Kg/m2 and 98${\pm}$7.2% in female students(p<0.0001). Over 50% of the subjects were dissatisfied with their body shape; the degree of dissatisfaction with body shape was higher in those who believed themselves to be fat. Mean score of EAT-26 was higher in female students (10.78${\pm}$7.36) than male students(6.07${\pm}$4.39)(p<0.0001). The prevalence of high risk eating disorder group was 2.6% in male students, 11.4% in female students(p<0.0001). Eating behavior was better in female students than male(p<0.0001). Eating behavior was significantly higher in eating disorder risk group in both sex. Therefore eating disorder symptomatology was highly prevalent among high school students in Daejeon. And this symptomatology has a more close relationship with physique status and eating behavior in female students.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.10-20
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• 2007

For spacecraft attitude control, reaction wheel (RW) steering laws with more than three wheels for three-axis attitude control can be derived by using a control allocation (CA) approach.1-2 The CA technique deals with a problem of distributing a given control demand to available sets of actuators.3-4 There are many references for CA with applications to aerospace systems. For spacecraft, the control torque command for three body-fixed reference frames can be constructed by a combination of multiple wheels, usually four-wheel pyramid sets. Multi-wheel configurations can be exploited to satisfy a body-axis control torque requirement while satisfying objectives such as minimum control energy.1-2 In general, the reaction wheel steering laws determine required torque command for each wheel in the form of matrix pseudo-inverse. In general, the attitude control command is generated in the form of a feedback control. The spacecraft body angular rate measured by gyros is used to estimate angular displacement also.⁵ Combination of the body angular rate and attitude parameters such as quaternion and MRPs(Modified Rodrigues Parameters) is typically used in synthesizing the control command which should be produced by RWs.¹ The attitude sensor signals are usually corrupted by noise; gyros tend to contain errors such as drift and random noise. The attitude determination system can estimate such errors, and provide best true signals for feedback control.⁶ Even if the attitude determination system, for instance, sophisticated algorithm such as the EKF(Extended Kalman Filter) algorithm⁶, can eliminate the errors efficiently, it is quite probable that the control command still contains noise sources. The noise and/or other high frequency components in the control command would cause the wheel speed to change in an undesirable manner. The closed-loop system, governed by the feedback control law, is also directly affected by the noise due to imperfect sensor characteristics. The noise components in the sensor signal should be mitigated so that the control command is isolated from the noise effect. This can be done by adding a filter to the sensor output or preventing rapid change in the control command. Dynamic control allocation(DCA), recently studied by Härkegård, is to distribute the control command in the sense of dynamics⁴: the allocation is made over a certain time interval, not a fixed time instant. The dynamic behavior of the control command is taken into account in the course of distributing the control command. Not only the control command requirement, but also variation of the control command over a sampling interval is included in the performance criterion to be optimized. The result is a control command in the form of a finite difference equation over the given time interval.⁴ It results in a filter dynamics by taking the previous control command into account for the synthesis of current control command. Stability of the proposed dynamic control allocation (CA) approach was proved to ensure the control command is bounded at the steady-state. In this study, we extended the results presented in Ref. 4 by adding a two-step dynamic CA term in deriving the control allocation law. Also, the strict equality constraint, between the virtual and actual control inputs, is relaxed in order to construct control command with a smooth profile. The proposed DCA technique is applied to a spacecraft attitude control problem. The sensor noise and/or irregular signals, which are existent in most of spacecraft attitude sensors, can be handled effectively by the proposed approach.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.177-181
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• 2016

This cross-sectional descriptive and qualitative study was aimed to study the people participation and their approaches toward the human carcinogenic liver fluke, Opisthorchis viverrini, prevention and control in Ban Chaun sub-district administrative organization (BCSAO) and Bamnet Narong sub-district municipality (BNSM), Bamnet Narong district, Chaiyaphum Province, Thailand between June 2013 and February 2014. Participants were purposive selected, included chiefs of sub-district administrative organizations, sub-district municipalities, sub-district health promotion hospitals (SHPHs), heads of village, and a further sample was selected with a multi-stage random sampling for public health volunteers, and villagers. The pre-designed questionnaire contained items for individualized status and the participatory steps of sharing ideas, decision-making, and planning, procession, evaluation, and mutual benefit, for the project O. viverrini prevention and control (POPC). In-depth interviews were used for collection of need approaches to POPC. With 375 participants who completed the questionnaire, it was found that people had a high level regarding to participate in the POPC, particularly in the process stage ($\bar{X}=3.78$, S.D. = 0.56), but the lowest level was found in sharing ideas, decision making, and planning step ($\bar{X}=3.65$, S.D. = 0.63). By comparison, participant status and organization did not significantly differ with people participation. In each step, Ban Chaun sub-district had a high level of participation in the step of sharing ideas, decision making, and planning toward POPC, more than Bamnet Narong sub-district municipality (t=2.20, p=0.028). Approaches for POPC in Ban Chaun sub-district and Bamnet Narong sub-district municipality included requirements for budget support, annual campaigns for liver fluke prevention and control, campaign promotion, risk group observation, home visiting, community rules regarding reducing raw fish consumption in their communities, and a professional public health officer for working in their communities, BCSAO, BNSM, and SHPH, for O. viverrini prevention and control. This study indicates that people realize that eradication of the liver fluke needs a continuous people participation for O. viverrini prevention and control in their communities.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.231-234
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• 2016

Opisthorchis viverrini infection is associated with cholangiocarcinoma particularly in the cases of chronic or re-infection. This presents a serious health problem in northeastern and northern Thailand. A community base approach is required for surveillance. Therefore, in a pilot project, re-examination of O. viverrini infection was conducted in the 3 districts of Nakhon Ratchasima province, Thailand, during June and October 2015. A total of 355 participants from a 194,152 population, was selected through multi-stage sampling. O. viverrini infection was determined using modified Kato Katz thick smear technique. Participants were 229 males and 126 females, and aged ${\geq}30$ years old. Prevalence of O. viverrini infection was 2.25% (8/355 participants). O. viverrini infection was slightly higher in females (3.17%), and age group between 41-50 years (4.49%). Mueang Yang district had a highest of O. viverrini infection rate (2.82%), and followed by Bua Yai (2.48%), and Chum Phuang (1.84%), respectively. O. viverrini infection rate was increased from year 2012 to 2015 particularly in Bua Yai and Mueang Yang. These re-examinion results indicate that opisthorchiasis is still problem in community of Nakhon Ratchasima province, therefore, the provincial-wide scale is need required. Furthermore health education is need intervened in the infected group, and screening of cholangiocarcinoma is urgently concerned.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.7
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• pp.3239-3245
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• 2014

Background: College students are recommended as the target groups for catch-up human papillomavirus (HPV) vaccination. Systematical exploration of awareness, acceptability, and decision-making factors of HPV vaccination among Chinese college students has been limited. Materials and Methods: A multi-center survey was conducted in mainland China between November 2011 and May 2012. College students aged 18-22 years were stratified by their grade, gender, and major for sampling. Socio-demographic and HPV-related information such as knowledge, perceptions, acceptability, and attitudes were collected through a questionnaire. Results: A total of 3,497 undergraduates completed the questionnaire, among which 1,686 were males. The acceptability of the HPV vaccine was high (70.8%). Undergraduates from high-level universities, at lower grade, or with greater prior knowledge of HPV vaccines showed higher acceptability of HPV vaccination ($p_{trend}$ <0.001). Additionally, undergraduates with vaccination experience outside the National Expanded Program on Immunization (OR=1.29; 95%CI: 1.10-1.51) or fear of HPV-related diseases (OR=2.79; 95%CI: 2.28-3.41) were more willing to accept HPV vaccination. General knowledge of HPV vaccine was low among undergraduates, and safety was a major concern (71.05%). The majority of students wished to pay less than 300RMB for HPV vaccine and chose the Chinese Center for Disease Control and Prevention as the most appropriate venue for vaccination. Conclusions: Although most undergraduates demonstrate positive attitudes towards HPV vaccination, challenges pertaining to introduction exist in China. Corresponding proactive education and governmental subsidy to do so are urgently needed by this age-group population. Suggestions and potential strategies indicated may help shape the future HPV vaccination program in China.

• Journal of Korean Society of Forest Science
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• v.81 no.1
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• pp.21-29
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• 1992

This study was conducted to provide basic information for deciding silvicultural system appropriate to a natural mixed stand in Jindong-Ri. For this, the stand structure such as DBH distribution, height distribution, and volume per DBH class were analyzed and the possibility of selection cutting as a silvicultural system was discussed. The DBH structure of the stand has reverse J-shaped diameter distribution which is typical in a selection cutting stand. The possibility of selection cutting is also accepted in the height structure by showing multi-storied height distribution of the stand. On the other hand, volume structure per DBH class did not show the mature stand of selection cutting due mainly to the lack of number of trees at 30cm DBH class and above. It seems that the unclear part of stand structure should be solved by further studies. Also, the rate of increment for DBH and volume should be estimated to predict the future stand structure.