• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.1
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• pp.14-21
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• 2004

Most adjustable-speed drives (ASDs) designed to operate low voltage induction motors incorporate voltage-source inverters (VSIs), which create motor voltages at high switching frequencies. The motor leads used to connect an ASD to a motor can behave like transmission lines for voltage pulses, which can be reflected at the motor terminals. The resulting oscillatory transient, known as the long-lead effect, can stress and consequently degrade the stator insulation system of a motor. This paper describes the results of tests to 1) determine the correlation between peak motor voltage and the length of motor leads and 2) determine the correlation between peak motor voltage and the switching frequency of the ASD Insulation failures like this usually are caused by voltage surges. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1733-1738
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• 2008

The treatment efficiency of rotating biological contactors (RBCs) for the high strength of dairy wastewater was investigated. Two different systems were conducted composing of a single RBC with tapered aeration reactors for the system A and a sequential RBCs following tapered aeration reactors for the system B. Experiments using dairy wastewater were conducted for 50 days period of time, in which hydraulic rates were maintained at the constant ratios of 346L per day and variable BOD concentrations were at the range from 1,358mg/L to 829mg/L, the $COD_{cr}$, concentration of the range were from 2,384mg/L to 1,329mg/L, the range of T-N concentrations was from 66mg/L to 38mg/L, and 50% of internal recycle and 50% of sludge return were performed. Results indicated that the removal efficiencies of the system B were higher than those of the system A. The removal efficiencies of system A for the BOD, $COD_{cr}$, T-N and T-P were 97.8%, 96.7%, 87.2% and 82%, respectively. The removal efficiencies of system B for the BOD, $COD_{cr}$, T-N and T-P were as of 98.5%, 98.5%, 91.3% and 89%.

• Journal of Biomedical Engineering Research
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• v.36 no.2
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• pp.48-53
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• 2015

Sudden infant death syndrome(SIDS) continues to be general cause of infant death. Also, apnea is supposed to be one of the main risk factor of SIDS. Therefore, Infant's respiratory monitoring and real-time apnea detection is very important to prevent SIDS. In this study, we proposed a non-contact home monitoring system for infant's respiration using Doppler radar in order to prevent SIDS. The respiration data were acquired from a commercialized baby simulator(Simbaby$^{TM}$) using a Doppler radar. To evaluate a performance of the proposed system, the simulator was placed in a supine and prone position and the chest belt was used simultaneously as a reference signal. As a result, correlation coefficients between respiration rates of Doppler radar and the chest belt in each position were 0.95(p < 0.001) and 0.98(p < 0.001), respectively. The averages of difference were $-0.29{\pm}5.21(mean{\pm}1.96{\cdot}$ standard deviation) in supine and $-0.12{\pm}3.05$ in prone from Bland-Altman analysis. The results indicated an excellent performance in detecting apnea with a sensitivity of 100% and a positive predictive value of 100% in each posture respectively. These results demonstrated that a proposed Doppler radar system is suitable for non-contact respiratory monitoring in order to prevent SIDS of infant.

• The Korean Journal of Nuclear Medicine Technology
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• v.26 no.1
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• pp.27-32
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• 2022

Purpose When performing a whole-body bone scan, many patients are experiencing psychological difficulties due to the close distance to the detector. Recently, in the medical field, there is a report that using virtual reality (VR) equipment can give pain relief to pediatric patients with weak concentration or patients receiving severe treatment through a distraction method. Therefore, in this paper, VR equipment was used to provide psychological stability to patients during nuclear medicine tests, and it is intended to evaluate whether it can be used in clinical practice. Materials and Methods As VR equipment, ALLIP Z6 VR (ALLIP, Korea) was used and the experiment was conducted after connecting to a mobile phone. The subjects were 30 patients who underwent whole-body bone examination from September 1, 2021 to September 30, 2021. After intravenous injection of 99mTc-HDP, 3 to 6 hours later, VR equipment was put on and whole body images were obtained. After the test, a survey was conducted, and a Likert scale of 5 points was used for psychological anxiety and satisfaction with VR equipment. Hypothesis verification and reliability of the survey were analyzed using SPSS Statistics 25 (IBM, Corp., Armonk, NY, USA). Results Anxiety about the existing whole-body bone test was 3.03±1.53, whereas that of anxiety after wearing VR equipment was 2.0±1.21, indicating that anxiety decreased to 34%. When regression analysis of the effect of the patient's concentration on VR equipment on anxiety about the test, the B value was 0.750 (P<0.01) and the t value was 6.181 (P<0.01). decreased and showed an influence of 75%. In addition, overall satisfaction with VR equipment was 3.76±1.28, and the intention to reuse was 66%. The Cronbach α value of the reliability coefficient of the questionnaire was 0.901. Conclusion When using VR equipment, patients' attention was dispersed, anxiety was reduced, and psychological stability was found. In the future, as VR equipment technology develops, it is thought that if the equipment can be miniaturized and the resolution of VR content images is increased, it can be used in various clinical settings if it provides more realistic stability to the patient.

• The Korean journal of internal medicine
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• v.33 no.6
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• pp.1194-1202
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• 2018

Background/Aims: This study evaluated the role of hypomethylating agents (HMA) compared to best supportive care (BSC) for patients with high or very-high (H/VH) risk myelodysplastic syndrome (MDS) according to the Revised International Prognostic Scoring System. Methods: A total of 279 H/VH risk MDS patients registered in the Korean MDS Working Party database were retrospectively analyzed. Results: HMA therapy was administered to 205 patients (73.5%), including 31 patients (11.1%) who then received allogeneic hematopoietic cell transplantation (allo-HCT), while 74 patients (26.5%) received BSC or allo-HCT without HMA. The 3-year overall survival (OS) rates were $53.1%{\pm}10.7%$ for allo-HCT with HMA, $75%{\pm}21.7%$ for allo-HCT without HMA, $17.3%{\pm}3.6%$ for HMA, and $20.8%{\pm}6.9%$ for BSC groups (p < 0.001). In the multivariate analysis, only allo-HCT was related with favorable OS (hazard ratio [HR], 0.356; p = 0.002), while very poor cytogenetic risk (HR, 5.696; p = 0.042), age ${\geq}65years$ (HR, 1.578; p = 0.022), Eastern Cooperative Oncology Group performance status (ECOG PS) 2 to 4 (HR, 2.837; p < 0.001), and transformation to acute myeloid leukemia (AML) (HR, 1.901; p = 0.001) all had an adverse effect on OS. Conclusions: For the H/VH risk group, very poor cytogenetic risk, age ${\geq}65years$, ECOG PS 2 to 4, and AML transformation were poor prognostic factors. HMA showed no benefit in terms of OS when compared to BSC. Allo-HCT was the only factor predicting a favorable long-term outcome. The use of HMA therapy did not seem to have an adverse effect on the transplantation outcomes. However, the conclusion of this study should be carefully interpreted and proven by large scale research in the future.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.48-58
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• 1995

This study was performed to find out the exposure level of mixed organic solvents, excretion of urinary hippuricacid and subjective symptoms according to the exposure of organic solvents of female workers who works on 5 shoes manufacturing industries in Taejon City from 24, september to 20, october 1993. The studied groups were divided into 3 groups that were consist of direct exposure group(48 workers), indirect exposure group(49 workers) and non-exposure group(68 workers) to the organic solvents. The exposure levels of toluene of direct exposure group which $89.86{\pm}56.20ppm$ had higher than that of indirect exposure group which had $40.23{\pm}47.21ppm$. In the exposure level of mixed organic solvent(R-value), direct exposure group was $2.84{\pm}1.53$ and exceeded approximatly 3 times the R-value. Whereas, indirect exposure group was not exceeded the R-value as $0.80{\pm}0.61$. In the excretion level of urinary hippuric acid, direct exposure group was $1.78{\pm}1.25g/l$, indirect exposure group was $1.22{\pm}0.93g/l$ and non-exposure group was $0.51{\pm}0.18g/l$ respectively. Therefore both direct exposure group and indirect exposure group were significantly higher than non-exposure group(P<0.01). In the correlation between toluene levels and urinary hippuric acid level, the direct exposure group had positive correlation(R=0.8309, P<0.01), also indirect exposure group had positive correlation(R=0.5859, P<0.05) and also in the correlation between the R value of mixed organic solvents and the urinary hippuric acid levels, the direct exposure group had positive correlation(R=0.4492, P<0.05), and indirect exposure group had ositive correlation(R=0.7911, P<0.01). In the complain rates of the worker's subjective symptoms at work, both direct exposure group and indirect exposure group were higher than non-exposure group(P<0.05, P<0.01). But the sujective symptoms of "floating sensation" of direct exposure group had significantly higher than indirect exposure group. In the percent of subjective symptoms complaints during the worker's daily life, both direct exposure group and indirect exposure group had generally more statistical significance than nonexposure group(P<0.01), direct exposure group had not statistical significant difference from indirect exposure group. As the results mentioned above, it has been analysed that the indirect at the adjacent manufaturing process are exposed to the considerable amount of solvent. Therefore, I think that there should be the betterment of surrounding through the complete working environment management to the occurrence source of the organic solvent, the changes of health management system to the indirect-exposed workers, and the systematic management of the special medical examination and the like.

• Korean Journal of Radiology
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• v.24 no.4
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• pp.274-283
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• 2023

Objective: To compare the outcomes of digital breast tomosynthesis (DBT) screening combined with ultrasound (US) with those of digital mammography (DM) combined with US in women with dense breasts. Materials and Methods: A retrospective database search identified consecutive asymptomatic women with dense breasts who underwent breast cancer screening with DBT or DM and whole-breast US simultaneously between June 2016 and July 2019. Women who underwent DBT + US (DBT cohort) and DM + US (DM cohort) were matched using 1:2 ratio according to mammographic density, age, menopausal status, hormone replacement therapy, and a family history of breast cancer. The cancer detection rate (CDR) per 1000 screening examinations, abnormal interpretation rate (AIR), sensitivity, and specificity were compared. Results: A total of 863 women in the DBT cohort were matched with 1726 women in the DM cohort (median age, 53 years; interquartile range, 40-78 years) and 26 breast cancers (9 in the DBT cohort and 17 in the DM cohort) were identified. The DBT and DM cohorts showed comparable CDR (10.4 [9 of 863; 95% confidence interval {CI}: 4.8-19.7] vs. 9.8 [17 of 1726; 95% CI: 5.7-15.7] per 1000 examinations, respectively; P = 0.889). DBT cohort showed a higher AIR than the DM cohort (31.6% [273 of 863; 95% CI: 28.5%-34.9%] vs. 22.4% [387 of 1726; 95% CI: 20.5%-24.5%]; P < 0.001). The sensitivity for both cohorts was 100%. In women with negative findings on DBT or DM, supplemental US yielded similar CDRs in both DBT and DM cohorts (4.0 vs. 3.3 per 1000 examinations, respectively; P = 0.803) and higher AIR in the DBT cohort (24.8% [188 of 758; 95% CI: 21.8%-28.0%] vs. 16.9% [257 of 1516; 95% CI: 15.1%-18.9%; P < 0.001). Conclusion: DBT screening combined with US showed comparable CDR but lower specificity than DM screening combined with US in women with dense breasts.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.234-244
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• 2021

Purpose: To date, studies of firearm and explosive injuries in the Korean military have been limited compared to its importance. To overcome this, this study examined the characteristics of musculoskeletal damages in soldiers who have suffered firearm and explosive injuries over the past four years. Materials and Methods: From January 2015 to July 2019, military forces who had suffered musculoskeletal injuries from firearms or explosive substances were included. The medical records and radiographs were reviewed retrospectively, and telephone surveys about Short Musculoskeletal Functional Assessment (SMFA) for this group were conducted. To compare the functional outcomes, statistical analysis was performed using a t-test for the types of weapons, and ANOVA for others. Results: Of the 61 patients treated for firearms and explosives injuries, 30 patients (49.2%) were included after undergoing orthopedic treatment due to musculoskeletal injury. The average age at injury was 26.4 years old (21-52 years old). The number of officers and soldiers was similar. Eleven were injured by gunshot and 19 by an explosive device. Sixteen were treated in the Armed Forces Capital Hospital and 10 at private hospitals. More than half of the 16 patients (53.3%) with a fracture had multiple fractures. The most common injury site was the hand (33.3%), followed by the lower leg (30.0%). There were 14 patients (46.7%) with Gustilo-Anderson classification 3B or higher who required a soft tissue reconstruction. Fifteen patients agreed to join the SMFA survey for the functional outcomes. Between officers and soldiers, officers had better scores in the Bother Index compared to soldiers (p=0.0045). Patients treated in the Armed Forces Capital Hospital had better scores in both the Dysfunction and Bother Index compared to private hospitals (p=0.0008, p=0.0149). Conclusion: This is the first study to analyze of weapons injuries in the Korean military. As a result of the study, the orthopedic burden was high in the treating patients with military weapon injuries. In addition, it is necessary to build a military trauma registry, including firearm and explosive injuries, for trauma treatment evaluation and development of military trauma system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.335-335
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• 2008

Phosphate glass samples with various $Cr_2O_3$ and $Er_2O_3$ contents based upon $55P_2O_5\cdot24BaO\cdot10K_2O\cdot4Al_2O_3\cdot6Yb_2O_3$ were prepared. The prepared glass compositions are dehydrated using gas bubble flow method in open system and investigated the effects of the eliminating of OH groups from the glass melts with bubbling time. It was found that the probability of $Er^{+3}$ fluorescence quenching by OH groups oscillations linear depends upon the OH groups absorption coefficients in the maximum of the stretch vibrations band at $3500cm^{-1}$ while $Er^{+3}$ concentration range is between $1.6\times10^{19}$ and $21.2\times10^{19}$ ion/$cm^3$.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.17-21
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• 2018

A series of laboratory scale experiments were performed to investigate the feasibility of membrane separation technology for natural rubber (NR) wastewater treatment and reuse. Three types of spiral wound membranes were employed in the cross-flow experiments. The NR wastewater pretreated by sand filtration and cartridge filtration was forced to pass through the ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes successively. The UF retentate, which containing abundant proteins, can be used to produce fertilizer, while the NF retentate is rich in quebrachitol and can be used to extract quebrachitol. The permeate produced by the RO module was reused in the NR processing. Furthermore, about 0.1wt% quebrachitol was extracted from the NR wastewater. Besides, the effluent quality treated by the membrane processes was much better than that of the biological treatment. Especially for total dissolved solids (TDS) and total phosphorus (T-P), the removal efficiency improved 53.11% and 49.83% respectively. In addition, the removal efficiencies of biological oxygen demand (BOD) and chemical oxygen demand (COD) exceeded 99%. The total nitrogen (T-N) and ammonia nitrogen (NH4-N) had approximately similar removal efficiency (93%). It was also found that there was a significant decrease in the T-P concentration in the effluent, the T-P was reduced from 200 mg/L to 0.34 mg/L. Generally, it was considered to be a challenging problem to solve for the biological processes. In brief, highly resource utilization and zero discharge was obtained by membrane separation system in the NR wastewater treatment.