• The Korean Journal of Pain
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• 제22권1호
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• pp.39-46
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• 2009

Background: Ketamine has an indirect sympathetic stimulation effect. We investigated heart rate variability (HRV) as a marker of cardiac autonomic function after a target controlled infusion (TCI) of ketamine with a plasma concentration of 30 or 60 ng/ml. Methods: In 20 adult volunteers, the mean of the R wave to the adjacent R wave interval (RRI), the range of RRI, the root mean square successive difference of intervals (RMSSD), the total power, the low frequency (LF, 0.04-0.15 Hz) power, the high frequency (HF, 0.15-0.4 Hz) power, the normal unit HF (nuHF), the normal unit LF (nuLF), the LF/HF ratio and the SD1 and the SD2 in the Poincare plot were measured before and after a TCI of ketamine. We observed for any psychedelic symptoms or sedation. Results: There were no differences in the mean and range of the RRI, RMSSD, total power, LF power, HF power, nuHF, nuLF, LF/HF ratio, SD1 and SD2 between before and after ketamine administration. The OAA/S score was higher and there were more psychedelic symptoms with a 60 ng/ml plasma concentration than with a 30 ng/ml plasma concentration. Conclusions: This study did not show any effect of a low plasma concentration of ketamine on the autonomic nervous system.

• The Journal of Internal Korean Medicine
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• 제27권4호
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• pp.836-844
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• 2006

Background: Mahuang (Ephedra sinica STAPF) is well known as an herbal medicine and has been widely used to reduce body weight and increase athletic ability. However, as a result of reporting many cases of adverse effects on the cardiovascular system, use of dietary supplements containing ephedra was prohibited by the FDA. Objectives : The object of this study was to find the effectiveness of ephedra on weight loss without severe adverse effect. Methods : 16 healthy volunteers consisting of an ephedra group (N=8) and a placebo group (N=8) were investigated. Study form was a randomized, controlled, double-blind clinical trial. The ephedra group took 12g of ephedra while the placebo group took 12g of glutinous rice powder. Both groups were measured with BCA (body composition analysis) on weight loss and with HRV (heart rate variability) on its adverse effect before and after medication. Results : The following results were obtained after taking 12g of ephedra for 14 days. In the ephedra group, body weight reduced significantly. In the placebo group, there were no significant differences of body weight between before and after placebo treatment. There was a slight increase of heart beat rate and deactivation of cardiac activity. Parasympathetic nerves were deactivated, but balances of autonomic nervous system were well maintained. Conclusions : The results suggest that ephedra in healthy adults tends to reduce body weight and deactivation of autonomic nervous system and cardiac activity.

• Journal of the Korea Society for Simulation
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• 제29권2호
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• pp.83-93
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• 2020

Bivariate measure of risk and error(BMORE) plot is originally designed to depict bivariate output data and related statistics obtained from a stochastic simulation such as sample mean, median, outliers, and a boundary of a certain percentile of simulation data. When compared to the static numbers, the plot has a big advantage in visualization that enables scholars and practitioners to understand the potential variability and risk in the simulation data. In this study, beyond just the construction of the plot to depict the variability of a certain system, we add a chance constraint to the plot and apply it for decision making such as checking the feasibility of systems, comparing performances of the systems on statistical background, and also analyzing the sensitivity of the problem parameters. In order to demonstrate an application of the plot, we employ an inventory management problem as an example. However, the techniques and algorithms suggested in this paper can be applied to any other problems comparing systems on bivariate performance measures with simulation/experiment results.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제39권
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• pp.23.1-23.8
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• 2017

Background: The aim of this study is to validate a new three-dimensional craniofacial stereophotogrammetry imaging system (3dMDface) through comparison with manual facial surface anthropometry. The null hypothesis was that there is no difference between craniofacial measurements using anthropometry vs. the 3dMDface system. Methods: Facial images using the new 3dMDface system were taken from six randomly selected subjects, sitting in natural head position, on six separate occasions each 1 week apart, repeated twice at each sitting. Exclusion criteria were excess facial hair, facial piercings and undergoing current dentofacial treatment. 3dMDvultus software allowed facial landmarks to be marked and measurements recorded. The same measurements were taken using manual anthropometry, using soluble eyeliner to pinpoint landmarks, and sliding and spreading callipers and measuring tape to measure distances. The setting for the investigation was a dental teaching hospital and regional (secondary and tertiary care) cleft centre. The main outcome measure was comparison of the craniofacial measurements using the two aforementioned techniques. Results: The results showed good agreement between craniofacial measurements using the 3dMDface system compared with manual anthropometry. For all measurements, except chin height and labial fissure width, there was a greater variability with the manual method compared to 3D assessment. Overall, there was a significantly greater variability in manual compared with 3D assessments (p < 0.02). Conclusions: The 3dMDface system is validated for craniofacial measurements.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제39권
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• pp.4.1-4.7
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• 2017

Background: This study is a quantitative evaluation of the influence of the mentolabial angle on perceived attractiveness and threshold values of desire for surgery. Methods: The mentolabial angle of an idealized silhouette male Caucasian profile image was altered incrementally between $84^{\circ}$ and $162^{\circ}$. Images were rated on a Likert scale by pretreatment orthognathic patients (n = 75), lay people (n = 75) and clinicians (n = 35). Results: A mentolabial angle of approximately $107^{\circ}$ to $118^{\circ}$ was deemed the most attractive, with a range of up to $140^{\circ}$ deemed acceptable. Angles above or below this range were perceived as unattractive, and anything outside the range of below $98^{\circ}$ or above $162^{\circ}$ was deemed very unattractive. A deep mentolabial angle ($84^{\circ}$) or an almost flat angle ($162^{\circ}$) was deemed the least attractive. In terms of threshold values of desire for surgery, for all groups, a threshold value of ${\geq}162^{\circ}$ and ${\leq}84^{\circ}$ indicated a preference for surgery, although clinicians were least likely to suggest surgery. The clinician group was the most consistent, and for many of the images, there was some variation in agreement between clinicians and lay people as to whether surgery is required. There was even more variability in the assessments for the patient group. Conclusions: It is recommended that in orthognathic and genioplasty planning, the range of normal variability of the mentolabial angle, in terms of observer acceptance, is taken into account as well as threshold values of desire for surgery. The importance of using patients as observers in attractiveness research is stressed.

• Proceedings of the KOSOMBE Conference
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.368-371
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• 1996

Background: Recently, measure of heart rate variability and the nonlinear "complexity" of heart rate dynamics have been used as indicators of cardiovascular health. Several investigators have demonstrated that heart rate variability decreased in aging, congestive heart failure and coronary heart disease. Because hypertensive patients showed alternation of cardiovascular homeostasis, we designed this study to evaluate the effect of anesthesia in hypertensive patients with approximate entropy (ApEn). Methods: With informed consent, eighteen normotensive patients and eighteen hypertensive patients were given no premedication. ECG data were collected from 10 minutes before induction to 15 minutes after induction. Collected ECG data were stored into computer binary files. We calculated ApEn from the collected ECG data. Results: Before induction, ApEn of hypertensive patients was significantly lower than normotensive patients(p<0.05). During induction and maintain of anesthesia, there was no difference of ApEn between two groups. During induction and maintain of anesthesia, in normotensive group, ApEn was significantly lower than that of preinduction(p<0.05). And ApEn during maintain of anesthesia was lower than that of induction(p<0.05). During maintain of anesthesia, in hypertensive group, ApEn was significantly lower than that of preinduction(p<0.05). Conclusions: Before induction, ApTn of hypertensive patients is significantly lower than normotensive patients. As anesthesia was deepened, ApEn of two groups were decreased. Because the baroreflex of hypertensive patients is already decreased, decreasing of ApEn of hypertensive patients during anesthesia is less than that of normotnesive patients.

• Safety and Health at Work
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• 제8권4호
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• pp.364-370
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• 2017

Background: Labeled noise reduction (NR) data presented by manufacturers are considered one of the main challenging issues for occupational experts in employing hearing protection devices (HPDs). This study aimed to determine the actual NR data of typical HPDs using the objective fit testing method with a microphone in real ear (MIRE) method. Methods: Five available commercially earmuff protectors were investigated in 30 workers exposed to reference noise source according to the standard method, ISO 11904-1. Personal attenuation rating (PAR) of the earmuffs was measured based on the MIRE method using a noise dosimeter (SVANTEK, model SV102). Results: The results showed that means of PAR of the earmuffs are from 49% to 86% of the nominal NR rating. The PAR values of earmuffs when a typical eyewear was worn differed statistically (p < 0.05). It is revealed that a typical safety eyewear can reduce the mean of the PAR value by approximately 2.5 dB. The results also showed that measurements based on the MIRE method resulted in low variability. The variability in NR values between individuals, within individuals, and within earmuffs was not the statistically significant (p > 0.05). Conclusion: This study could provide local individual fit data. Ergonomic aspects of the earmuffs and different levels of users experience and awareness can be considered the main factors affecting individual fitting compared with the laboratory condition for acquiring the labeled NR data. Based on the obtained fit testing results, the field application of MIRE can be employed for complementary studies in real workstations while workers perform their regular work duties.

• Journal of Korean Medical Science
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• 제33권43호
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• pp.239.1-239.12
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• 2018

Background: We described a novel multi-step retinal fundus image reading system for providing high-quality large data for machine learning algorithms, and assessed the grader variability in the large-scale dataset generated with this system. Methods: A 5-step retinal fundus image reading tool was developed that rates image quality, presence of abnormality, findings with location information, diagnoses, and clinical significance. Each image was evaluated by 3 different graders. Agreements among graders for each decision were evaluated. Results: The 234,242 readings of 79,458 images were collected from 55 licensed ophthalmologists during 6 months. The 34,364 images were graded as abnormal by at-least one rater. Of these, all three raters agreed in 46.6% in abnormality, while 69.9% of the images were rated as abnormal by two or more raters. Agreement rate of at-least two raters on a certain finding was 26.7%-65.2%, and complete agreement rate of all-three raters was 5.7%-43.3%. As for diagnoses, agreement of at-least two raters was 35.6%-65.6%, and complete agreement rate was 11.0%-40.0%. Agreement of findings and diagnoses were higher when restricted to images with prior complete agreement on abnormality. Retinal/glaucoma specialists showed higher agreements on findings and diagnoses of their corresponding subspecialties. Conclusion: This novel reading tool for retinal fundus images generated a large-scale dataset with high level of information, which can be utilized in future development of machine learning-based algorithms for automated identification of abnormal conditions and clinical decision supporting system. These results emphasize the importance of addressing grader variability in algorithm developments.

• Safety and Health at Work
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• 제12권4호
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• pp.445-451
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• 2021

Background: This study aimed to evaluate the reliability and validity of the self-administered questionnaire for Korean radiation workers. Methods: From May 24, 2016, to June 30, 2017, 20,608 participants completed the questionnaire, providing information on sociodemographics, lifestyle, work history and practices, medical radiation exposure, and medical history, which was linked to the National Dose Registry and the National Cancer Registry. The validity of the questionnaire was evaluated using the responses of 20,608 workers, and reliability was evaluated using the responses of 3043 workers who responded to the survey twice. Results: Responses concerning demographic characteristics and lifestyle showed reliability with a moderate-to-high agreement (kappa: 0.43-0.99), whereas responses concerning occupation and medical radiation exposure had a wide range of agreement (kappa: 0.05-0.95), possibly owing to temporal variability during employment. Regarding validity, responses to the question about the first year of employment had an excellent agreement with the national registry (intraclass correlation coefficient = 0.9); however, responses on cancer history had a wide range of agreement (kappa: 0.22-0.85). Conclusion: Although the reliability and validity of the questionnaire were not distinguished by demographic characteristics, they tended to be low among participants whose occupational radiation exposure was minimal. Overall, the information collected can be reliable for epidemiological studies; however, caution must be exercised when using information such as medical exposure and work practices, which are prone to temporal variability.

• Journal of Ecology and Environment
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• 제44권4호
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• pp.229-240
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• 2020

Background: Genus Quercus is a successful group that has occupied the largest area of forest around the world including South Korea. The acorns are an important food source for both wild animals and humans. Although the reproductive characteristics of this genus are highly variable, it had been rarely studied in South Korea. Therefore, in Seoraksan and Odaesan National Parks (i) we measured the acorn production of Quercus mongolica, an overwhelmingly dominant species in South Korea, for 3 years (2017-2019), (ii) evaluated the spatial-temporal variation of acorn production, and (iii) analyzed the effects of oak- and site-related variables on the acorn production. Results: The annual acorn production of Q. mongolica increased 36 times from 1.2 g m-2 in 2017 to 43.2 g m-2 in 2018, and decreased to 16.7 g m-2 in 2019, resulting in an annual coefficient of variation of 104%. The coefficient of spatial variation was high and reached a maximum of 142%, and the tree size was the greatest influencing factor. That is, with an increase in tree size, acorn production increased significantly (2018 F = 16.3, p < 0.001; 2019 F = 8.2, p < 0.01). Elevation and slope also significantly affected the production in 2019. However, since elevation and tree size showed a positive correlation (r = 0.517, p < 0.001), the increase in acorn production with increasing elevation was possibly due to the effect of tree size. The acorn production of Odaesan for 3 years was 2.2 times greater than that of Seoraksan. This was presumed that there are more distribution of thick oak trees and more favorable site conditions such as deep soil A-layer depth, high organic matter, and slower slopes. Conclusion: As reported for other species of the genus Quercus, the acorn production of Q. mongolica showed large spatial and annual variations. The temporal variability was presumed to be a weather-influenced masting, while the spatial variability was mainly caused by oak tree size.