• Journal of Convergence for Information Technology
• /
• v.10 no.10
• /
• pp.273-278
• /
• 2020

The aim of this study was to confirm the relationship between asthma and dental caries in Korean children. Using the data of the 2017 The Panel Study of Korean Children (PSKC), logistic regression analysis was performed to investigate the association between asthma and dental caries in 331,457 9-year-old children. As a result of this study, asthma was associated with dental caries(unadjusted odds ratio [OR]: 2.75, 95% confidence interval [CI]: 2.63-2.88). In addition, after all confounders were controled, their association became stronger(adjusted odds ratio [aOR]: 2.78, 95% confidence interval [CI]: 2.65-2.91). Further studies are needed to clearly confirm the relationship between respiratory disease and dental caries and their causal relationship in children.

• The Journal of Korean Physical Therapy
• /
• v.14 no.4
• /
• pp.385-397
• /
• 2002

Objectives: This study was to investigate the experience and a Point prevalence rate and factors related with Low Back Pain (LBP) in instructors of drive institute. Methods: Questionnaires were completed by 174 instructors who worked at 13 drive institutes in 4 small cities from June 2002. The information was used to estimate odds ratio (OR) and 95$\%$ confidence intervals (CI) for factors relation to LBP. A retrospective study design was used. Results: The experience rate for LBP was 57.2$\%$, 43.4$\%$ in one year interval prevalence, 42.2$\%$ in 6 months interval prevalence, and 35.8$\%$ in a point prevalence rate. Factor significantly associated with LBP experience by logistic regression was labour hour (p=0.0034), subjects who worked for long hours a day were higher than those who did not (OR=3.8, 95$\%$ CI 1.4-5.6). Conclusions: In conclusion, labour hour was significantly associated with LBP experience.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.8
• /
• pp.1907-1914
• /
• 1998

This paper proposes the adaptive connection admission cotrol using the variale MRR(measurement reflection ratio) and the distribution of the number of cells arriving during the fixed interval. This distribution is estimated from the measured number of cells arriving at the output buffer during the fixed interval and traffic parameters specified by user. MRR is varied by the difference of estimated distribution and measurement distribution. As MRR is adaptively varied by estimated distribution error of accepted connections, it quickly reduces estimation error. Also, the scheduling scheme is proposed for multiplexed traffic with various traffic characteristics. For each traffic class, this scheme estimates adaptively equivalent bandwidth and schedules according to equivalent bandwidth ratio of each traffic class, so it improves cell loss rate and link utilization.

• Safety and Health at Work
• /
• v.12 no.1
• /
• pp.108-113
• /
• 2021

Background: This study aimed to investigate the relationship between changes in employment status and new-onset depressive symptoms through a one-year follow-up of permanent waged workers. Methods: We analyzed the open-source data from the Korea Welfare Panel Study. Using the 2017 data, we selected 2,314 permanent waged workers aged 19 to 59 years without depressive symptoms as a base group. The final analysis targeted 2,073 workers who were followed up in 2018. In 2018, there were five categories of employment status for workers who were followed up: permanent, precarious, unemployed, self-employed, and economically inactive. Multiple logistic regression was used to determine the association between employment status change and new-onset depressive symptoms. Results: Adjusted multiple logistic regression analysis showed that among male workers, workers who went from permanent status to being unemployed (odds ratio: 4.50, 95% confidence interval: 1.19 to 17.06) and from permanent status to being precarious workers (odds ratio: 3.15, 95% confidence interval: 1.30 to 7.65) had significantly high levels of new-onset depressive symptoms compared with those who retained their permanent employment status. There were no significant increases in new-onset depressive symptoms of male workers who went from permanent status to being self-employed or economically inactive. On the other hand, no significant differences were found among female workers. Conclusion: Our study suggests that the change of employment status to precarious workers or unemployment can cause new-onset depressive symptoms in male permanent waged workers.

• Korean Journal of Materials Research
• /
• v.33 no.12
• /
• pp.537-549
• /
• 2023

The sintering shrinkage behaviors of low temperature cofired ceramics (LTCC) and resistors were compared using commercial LTCC and thick-film resistor pastes, and factors influencing the camber of cofired resistor/LTCC bi-layers were also investigated. The onset of sintering shrinkage of the resistor occurred earlier than that of LTCC in all resistors, but the end of sintering shrinkage of the resistor occurred earlier or later than that of LTCC depending on the composition of the resistor. The sintering shrinkage end temperature and the sintering shrinkage temperature interval of the resistor increased as the RuO₂/glass volume ratio of the resistor increased. The camber of cofired resistor/LTCC bi-layers was obtained using three different methods, all of which showed nearly identical trends. The camber of cofired resistor/LTCC bi-layers was not affected by either the difference in linear shrinkage strain after sintering between LTCC and resistors or the similarity of sintering shrinkage temperature ranges of LTCC and resistors. However, it was strongly affected by the RuO₂/glass volume ratio of the resistor. The content of Ag and Pd had no effect on the sintering shrinkage end temperature or sintering shrinkage temperature interval of the resistor, or on the camber of cofired resistor/LTCC bi-layers.

• Journal of Sensor Science and Technology
• /
• v.33 no.1
• /
• pp.1-6
• /
• 2024

This study aims to suggest the partition ratio (Q-factor) of healthy Koreans and the comparison results of breath alcohol concentration (BAC) measurements using two methods (photoacoustic and electrochemical methods) for developing breath alcohol ignition interlock devices (BAIIDs). Given the relationship between BACs and BrACs and the Q-factor, the alcohol metabolism of healthy Koreans (96 males and 91 females) is revealed for understanding the digestion of alcohol and surveying the fundamental data of alcohol-related problems, CO₂ concentrations vs. alcohol concentrations, and the performance of alcohol sensors in the marketplace. The average Q-factor of healthy Korean males and females are 1,913 (95% confidence interval from 1,889-1,937) and 1,991 (95% confidence interval from 1,945-2,036). Photoacoustic measurements could be applied to predict the BACs of drinkers, which is confirmed by the Bland-Altman plots presented in this study. The biases based on the partition ratios (Q=1,913 and Q=1,991) in the Bland-Altman plots were -0.0004% (95% CI from -0.0011 to +0.0003% for males) and -0.0017% (95% CI from -0.020 to +0.017% for females).

• Journal of Korean Neurosurgical Society
• /
• v.44 no.5
• /
• pp.320-326
• /
• 2008

Objective : To evaluate the risk factors that may be responsible for the development of contralateral reherniations from ipsilateral ones after open lumbar microdiscectomy (OLM), and to compare surgical outcomes of revision OLM for contralateral reherniations with those for ipsilateral ones. Methods: Seventeen patients who underwent revision OLM for contralateral reherniation were enrolled into Group I, and 35 patients who underwent revision OLM for ipsilateral reherniation were enrolled into Group II. Using medical charts and imaging study results, the differences in the clinical and radiological factors were evaluated between the two groups. Clinical outcomes of each group were compared between the two groups. Results: Significant differences were found in the interval to reherniation from initial surgery (33 months for Group I and 18.6 months for Group II, p=0.009), as well as in the incidences of both protruded disc (35.3% for Group I and 8.6% for Group II, p=0.045) and mild disc degeneration (29.4% for Group I and 5.7% for Group II, p=0.031) at initial surgery. On binary multi-logistic regression analysis, significant differences were found in the interval to reherniation (p=0.027, Odds ratio=1.051) and incidence of mild disc degeneration (p=0.025, Odds ratio= 12.03) between the two groups. There were no significant differences in the improvement of clinical outcomes after revision OLM between the two groups. Conclusion: The interval to reherniation from initial surgery and the grade of disc degeneration at initial surgery were key factors that distinguished the development of contralateral reherniations from ipsilateral ones. Surgical outcomes of revision OLM were similar in both groups.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.2
• /
• pp.179-184
• /
• 2005

An accurate evaluation of a production capacity is an important role for production planning in manufacturing industry. The study has been partly done about the fluctuation in the conventional study of the production capacity, but the study of the subordination has been hardly done. Therefore, in this paper, we will devide by the production capacity which is formed into the production subjects to evaluate objectively the differences of between the actual capacity and the designed capacity in manufacturing industry and will suggest production capacity estimation model which is considered the fluctuation and the subordination, the decreasing causes of the production capacity. The weight of fluctuation which is used for the computation of the ratio of fluctuation and the ratio of subordination and the subordination are denoted to the interval number Thus, the production capacity is denoted to the interval numbers. The efficiency of the proposed model will show through the case study.

• Korean Journal of Veterinary Research
• /
• v.14 no.2
• /
• pp.253-268
• /
• 1974

A total of 331 dairy cattle in Jeonnam area were examined for the breeding status and hematological values during the period from June to August. 1971 and 1974. The data obtained were analysed according to the status of breeding and the type of farm management. The results obtained in this work were summarized as follows: 1. 331 dairy cows were grouped as pregnant (63.81%) anestrus after parturition (12.45%), pregnancy unknown (11.48%), repeat breeder (10.32%), and others (1.94%). 2. The summery of reproductive histories and clinical examination were as follows. Average of calving interval was 16.5 months, interval from parturition to first breeding 97 days and postpartum interval to first estrus 72 days. Services per conception was 1.6 rate of postpartum estrus (60 days) 12.0%, and the rate of repent breeder 10.3%. 3. Generally, the blood values of RBC, Hb, serum total protein and A/G ratio were lower than those normal values, especially, the cows which showed abnormal values belonged to the repeat breeder and the unknown to conception group. The mean value for serum inorganic phosphorus was the normal value or hyperphosphatemia, on the other hand, the mean value for serum calcium of the repeat breeder group was the lowest than the other group. 4. Follow-up evaluations on the results of the laboratory tests strongly suggest that the problems of repeat breeder had a tendency to occur more frequently in the large herd (A and B type farm), and the Ca/P ratio of almost all the cows showed abnormal values.

• Journal of Welding and Joining
• /
• v.27 no.6
• /
• pp.17-24
• /
• 2009

The Friction Stir Welding(FSW) has mainly been used for making butt joints in Al alloys. Development of Friction Stir Lap Welding(FSLW) would expand the number of applications. Microstructure of FSLW in A5052-H112 alloy was investigated under varying rotation and welding speed. As the rotation speed was increased and the welding speed was decreased, a amount of heat was increased. As a result, bead interval was narrower, bead width are larger, and experimental bead interval was almost similar to theoretical bead interval. Typical microstructures of FSLW A5052-H112 alloy consist of three zones, including Stir Zone(SZ), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). As a amount of heat was increased, average grain size was larger in three zones. Nevertheless, the aspect ratio was almost fixed for FSLW conditions. The misorientation of SZ, HAZ and TMAZ was examined. A large number of low angle grain boundaries, which were formed by severe plastic deformation, were showed in TMAZ as comparison with SZ and HAZ. Microhardness distribution was high in order of BM, SZ, TMAZ, and HAZ. The Micro-hardness distribution in HAZ, TMAZ of upper plate were lager than lower plate. Relationship between average grain size and microhardness was almost corresponded to Hall-Petch equation.