• 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.

• Journal of dental hygiene science
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• v.15 no.4
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• pp.472-479
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• 2015

The purpose of this study is to examine musculoskeletal disorders and grasp the relationship between working environment factors and stress and musculoskeletal disorders in dental hygienists. The self-administered questionnaire survey was conducted with 483 dental hygienists working in Gwangju who were selected by convenience sampling. Frequency analysis, crosstab analysis, t-test, and multiple logistic regression analysis were made. Subjects' musculoskeletal disorders that complain of severe pains were 29.8%. The relationship between working environment factors and stress and musculoskeletal disorders were examined. As a result, work break frequency of working environment factors and stress were found to influence musculoskeletal disorders. For working environment factors, the odds ratio of musculoskeletal disorders of the two breaks group was 0.29 (95% confidence interval [CI], 0.11~0.73), compared with the no break group, indicating less musculoskeletal disorders. However, no significant difference was found in one break and more than three breaks groups. The odds ratio of musculoskeletal disorders of stress was 0.44 (95% CI, 0.27~0.70), indicating negative correlation. As break frequency was moderate (two breaks), musculoskeletal disorders became decreased. Stress showed negative correlation with musculoskeletal disorders.

• Journal of The Korean Society of Clinical Toxicology
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• v.8 no.1
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• pp.16-23
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• 2010

Purpose: Organophosphate insecticide poisoning is common in Korea, but there is no definitive guideline for determining the severity of the poisoning and the predictive factors. Therefore, we evaluated the organophosphate poisoned patients and we divided them into two groups, the survivors and the dead, and the results might be useful for treating organophosphate poisoning patients. Methods: We performed a retrospective analysis of 68 organophosphate poisoned patients who visited the Chosun University Hospital Emergency Medical Center during a 24-month period from January, 2007 to December, 2008. We made a work sheet of the patients' characteristics and the collected data was analyzed and we compared this data between the survivor group and the dead patient group. Results: There were significant differences between the survivor group and the dead patient group for the mean age, the alcohol intake state and the typically expressed signs. The dead patients had lower blood pressure, tachycardia and a lower Glasgo Coma Score (GCS) score than the survivor group. On the arterial blood gas analysis, the dead patients had more severe acidemia and they had lower saturations. Increased serum amylase levels were found in the dead patients. The survivors'initial and follow up serum pseudocholinesterase activity (after 6~8 days) was significantly higher than that of the dead group. The total amount of atropine injected to patient was less in the survivors than that in the dead patients. Conclusion: Old age and expressing the typical intoxication signs, a lower GCS score and blood pressure, showing acidosis on the gas analysis and low serum cholinesterase activity may be useful as poor prognostic indicators for patients with organophosphate poisoning. We suggest that physicians must pay careful attention to the signs and prognostic factors of organophosphate insecticide poisoned patients.

• 한국사회복지학회:학술대회논문집
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• 2002.04a
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• pp.497-531
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• 2002

It is very important for rehabilitation to deal with psychological aspects of persons with disabilities, as well as efforts improving the institutional and environmental conditions. A majority of persons with severe disabilities in the situation of Korea have difficulty in having and maintaining a job. Work should and would be a source of self-respect and material well-being in this modern society. Therefore, Vocational rehabilitation services are measures in restoration of family functions and social participation of persons with disabilities. This study aims at investigating linguistic characteristics and the validity of constructional concepts of picture interest test Inventories that have been utilized for the segregated groups of people such as persons with developmental disabilities. Picture interest test inventories seemed to be valid for measuring psychological traits and characteristics of people with mental retardation, and this finding can be extended to the group of other developmental disabilities, such as learning disabilities and mild/moderate behavioral deficits. The Holland classification system seemed to be best fitted for developing a comprehensive and accurate vocational interest inventory.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.147-156
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• 2016

This study analyzed the impact of changes in the construction business on construction company insolvency according to their size using the vector error correction model. First, this study applied EDF (Expected Default Frequency), which was calculated by KMV (Kealhofer, McQuown and Vasicek) model, as a variable to indicate the insolvency of construction companies. This study set 30 construction companies listed to KOSPI/KOSDAQ for estimating the EDF by size and construction companies were divided into two groups according to their size. To examine the construction business cycles, the amount of construction orders according to the type-residential, non-residential, and civil work- was used as a variable. The serial data was retrieved from TS2000 established by the Korea Listed Companies Association (KLCA), Statistics Korea. The analysis period was between the second quarter of 2001 and fourth quarter of 2015. As a result of calculating the EDF of construction companies by size, as it is generally known, the large-sized construction companies showed lower levels of insolvency than relatively smaller-sized construction companies. On the other hand, impulse response analysis based on VECM confirmed that the level of insolvency of large-scaled companies is more sensitive to business fluctuations than relatively smaller-sized construction companies, particularly changes in the residential construction market. Hence it is a major factor affecting the changes in insolvency of large-sized construction companies.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.62-65
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• 2008

Purpose: Vitamin $B_{12}$ and folic acid are type of water-soluble vitamin and those work as a secondary vital enzyme, but especially those are involved in the nuclear DNA synthesis. Those are mainly measured in order to diagnose megaloblastic anemia and to assess the storage of folic acid during pregnancy. It is generally known that the hemolyzed serum is useless for folic acid and vitamin $B_{12}$, but it is not easy to abide by this information because our lab (Samkwang Medical Laboratories) is reference laboratory. We tested how much the extent of hemolyzed serum had influence on the results. Materials and Method: We performed the tests of vitamin $B_{12}$, folic acid. For the hemolysis effect study, we used 40 cases. According to the level of A, B and C groups, each group had 10 samples which were mechanically hemolyzed serum. Results: Hemolysis did not affect the vitamin $B_{12}$ results. However in case of folic acid, the value increased according to the degree of hemolysis. And severe hemolyzed cases had the highest value (greater than 20 ng/ml). Conclusions: Preventing the hemolysis, it has to be informed that blood-collecting, separation and storage are performed more carefully. As you see from the above results, hemolyzed serum is not proper for folic acid test, and hemolysis does not affect the results of vitamin $B_{12}$. However, for the more accurate results, it is necessary to avoid hemolysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.243-244
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• 2013

Over the past 15 years, several groups have incorporated radio-frequency quadrupole (RFQ) based instruments before the accelerator in accelerator mass spectrometry (AMS) systems for ion-gas interactions at low kinetic energy (＜40 eV). Most AMS systems arebased on a tandem accelerator, which requires negative ions at injection. Typically, AMS sensitivity abundance ratios for radioactive-to-stable isotope are limited to Xr/Xs ＞10^-15, and the range of isotopes that can be analyzed is limited because of theneed to produce rather large negative ion beams and the presence of atomic isobaric interferences after stripping. The potential of using low-kinetic energy ion-gas interactions for isobar suppression before the accelerator has been demonstrated for several negative ion isobar systems with a prototype RFQ system incorporated into the AMS system at IsoTrace Laboratory, Canada (Ontario, Toronto). Requisite for any such RFQ system applied to very rare isotope analysis is large transmission of the analyte ion. This requires proper phase-space matching between the RFQ acceptance and the ion beam phase space (e.g. 35 keV, ${\varphi}3mm$, +-35 mrad), and the ability to control the average ion energy during interactions with the gas. A segmented RFQ instrument is currently being designed at Korea Institute for Science and Technology (한국과학기술연구원, KIST). It will consist of: a) an initial static voltage electrode deceleration region, to lower the ion energy from 35 keV down to ＜40 eV at injection into the first RFQ segment; b) the segmented quadrupole ion-gas interaction region; c) a static voltage electrode re-acceleration region for ion injection into a tandem accelerator. Design considerations and modeling will be discussed. This system should greatly lower the detection limits of the 6 MV AMS system currently being commissioned at KIST. As an example, current detection sensitivity of 41Ca/Ca is limited to the order of 10^-15 while the 41Ca/Ca abundance in modern samples is typically 41Ca/Ca~10^-14 - 10^-15. The major atomic isobaric interference in AMS is 41K. Proof-of-principal work at IsoTrace Lab. has demonstrated that a properly designed system can achieve a relative suppression of KF3-/41CaF3- ＞4 orders of magnitude while maintaining very high transmission of the 41CaF3- ion. This would lower the 41Ca detection limits of the KIST AMS system to at least 41Ca/Ca~10^-19. As Ca is found in bones and shells, this would potentially allow direct dating of valuable anthropological archives and archives relevant to our understanding of the most pronounced climate change events over the past million years that cannot be directly dated with the presently accessible isotopes.

• Journal of agricultural medicine and community health
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• v.40 no.2
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• pp.80-92
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• 2015

Objectives: To clarify the association between dust from large construction sites and allergic and respiratory conditions among residents in Sejong city. Methods: We included 379 individuals older than 50 years from three areas of Sejong city; two areas near construction sites and one area for a comparison. Prevalence of self-reported allergic and respiratory conditions was compared across the three areas using logistic regression to adjust for covariates including age, gender, smoking, and educational attainment. A total of 16 individuals were interviewed to take details of the residents' experiences of construction work. Results: Those living in the nearby areas around construction sites were generally found to have the increased prevalence for all allergic and respiratory conditions. Odds Ratio(OR)s for cough and sneezing among the six symptoms and allergic rhinitis among the three diagnosed diseases reached statistical significance but only OR for cough remained significant after adjustment: adjusted OR for cough was 2.63 (95% CI, 1.07-6.46). Two relevant themes emerged from semi-structured interview were; 1) most residents from the affected area reported a considerable level of exposure to construction dust, 2) about half of them noted that construction dust influences allergic- and respiratory health. Conclusions: General pattern provides suggestive evidence that living close to construction sites may be positively associated with elevated risks of allergic and respiratory conditions. Efforts should be made to establish preventive measures and a comprehensive in-depth health impact assessment on this issue.

• Journal of the Ergonomics Society of Korea
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• v.30 no.6
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• pp.695-703
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• 2011

Objective: This study was to investigate the effects of coordinated upper-limb body postures on the subjective discomfort rating, heart rate, and muscle activities. Background: Although generally many checklists such as OWAS, RULA, and REBA were applied to evaluate various body postures, the body postures were might be overestimated or underestimated because each body part(i.e., back, shoulder, and elbow etc.) was evaluated separately, and then added all rates of individual body parts to assess an overall risk level for the body posture in these methodologies. Methods: A total of 20 participants maintained 14 postures which were combinations of back, shoulder, and elbow flexion angles and then muscle activities, subjective discomfort, and heart rates were collected every three minute during a sustained 15 minute and 0.5kg weight holding task. Four muscle groups were investigated: erector spine, anterior deltoid, upper trapezius, triceps brachii. Results: Results showed that subjective discomfort was the lowest when the angle of back and shoulder were both $0^{\circ}s$, while the body posture with $45^{\circ}$ of back angle and $45^{\circ}$ shoulder angle was rated as the most subjective discomfort posture. In general, the subjective discomfort ratings increased as back and shoulder flexion angles increased. It was noted that, however, the subjective discomfort of body posture with a $45^{\circ}$ back angle and $45^{\circ}$ shoulder flexion angle was lower than that of body posture with a $0^{\circ}$ back and $45^{\circ}$ shoulder flexion angle. The research findings of heart rates and muscle activities showed similar results for the analyses of subjective discomfort ratings. Conclusions: The possible limitations of the current ergonomics evaluation techniques which assessing a body posture with summing all body part score after individually analyzed in this study. Based on the analyses of subjective discomfort, heart rate, and muscle activities, it was recommended that a use of effects of coordinated upper-limb body postures would be considered when one evaluates work-load for various working postures. Application: These findings can be used for developing a more accurate assessment checklist for working posture as well as preventing musculoskeletal disorders of workers in workplaces.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.289-296
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• 2014

The rebar detailing is an important work influencing the final performance and quality of RC structures. But it is one of the most irrational and illogical activity in construction site. Many groups of workers, including main contractors, structural engineers, shop drawers, rebar fabricators, and etc., participate in this activity. A loosely-organized process for this activity is apt to produce a big amount of rebar loss or even degraded structures. A 3-dimensional rebar auto-placing system, called as Rebar Hub, has been designed and implemented in this research. Rebar Hub provides a totally integrated service from 3D structural modeling of buildings to rebar auto-placing considering anchorage, splice, and the length of ordered rebar. In addition, Rebar Hub can recognize the 2D drawing CAD files and then build 3D structural models which are used for the start point of 3D rebar auto-placing. After rebar auto-placing, each members of the 3D structural model have rebar information belonging to them. It means that the rebar information can be used for the afterward works such as quantity-survey, manufacturing and fabrication of rebars. Rebar Hub is showing outstanding performance while applying to practical projects. It has almost five times productivity and reduces the rebar loss up to 3~8% of the initially-surveyed amount of rebar.