• 전기학회논문지P
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• 제53권1호
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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.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1733-1738
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• 2008

고농도 유가공폐수의 유기물 및 질소, 인의 제거효율을 비교하기 위하여 두 개의 반응 시스템을 구성하였다. 하나는 하나의 RBC 반응조와 3단 점감포기조로 구성한 시스템이며 다른 하나는 RBC 반응조 2개를 연속으로 구성하고 3단 점감포기조로 구성한 시스템이다. 본 연구에 적용한 바실러스 미생물은 RBC의 끈상미생물접촉재에 부착하여 수행하였다. 각 시스템으로 유입되는 유가공폐수의 BOD 평균농도는 988mg/L, 1,046mg/L이었으며, 유출수 BOD 농도는 21.4mg/L, 15.9mg/L로 제거율은 97.8%, 98.5%의 결과를 보였다. RBC 단일공정 유입수의 평균 $COD_{cr}$ 농도는 1,837mg/L, 유출수는 53.0mg/L로 96.7%의 제거 효율을 보였으며 RBC 연속공정 유입수의 평균 $COD_{cr}$ 농도는 1,852mg/L, 유출수는 평균 27.8mg/L로 98.5%의 제거효율을 보였다. 유입수 T-N 분석결과 RBC 단일공정은 평균 51.9mg/L로 측정되었고, RBC 연속반응공정에서의 유입수 평균은 54.3mg/L이었으며, 유출수는 각각 6.6mg/L, 4.7mg/L로 87.2%, 91.3%의 제거효율을 보였다. T-P에 대한 RBC 단일공정과 RBC 연속공정에서의 분석 결과 유입수 평균농도는 각각 8.9mg/L, 9.1mg/L로 측정되었고, 유출수 농도는 1.6mg/L, 1.0mg/L로 T-P 제거율은 82%, 89%로 나타났다.

• 대한의용생체공학회:의공학회지
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• 제36권2호
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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.

• 핵의학기술
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• 제26권1호
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• pp.27-32
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• 2022

전신 뼈 검사를 시행할 경우 검출기와 밀접한 거리로 인해 심리적 어려움을 겪고 있는 환자들이 많다. 최근 의료분야에서 가상현실(Virtual reality, VR) 장비를 사용하여 주의분산법(distraction method)을 통해 집중력이 약한 소아 환자 또는 중증 치료를 받는 환자에게 진통경감 효과를 줄 수 있다는 보고가 있다. 이에 본 논문은 핵의학 검사 시 환자들에게 심리적 안정을 주기 위해 VR 장비를 사용하였고, 이를 임상에서 활용할 수 있는지 평가해보고자 한다. VR 장비로는 ALLIP Z6 VR (ALLIP, Korea)을 사용하여 휴대전화에 연결한 후 실험을 진행하였다. 대상자는 2021년 9월 1일부터 2021년 9월 30일까지 전신 뼈 검사를 시행한 환자 30명으로 하였다. ^99mTc-HDP를 정맥주사한 후 3시간~6시간 뒤에 VR 장비를 착용하고 전신영상을 얻었다. 검사 후 설문조사를 실시하였고 검사에 대한 심리적 불안도와 VR 장비에 대한 만족도는 리커트 척도 5점을 이용하였다. 설문조사에 관한 가설검증 및 신뢰도는 SPSS Statistics 25 (IBM, Corp., Armonk, NY, USA)를 통해 분석하였다. 기존 전신 뼈 검사에 대한 불안감은 3.03±1.53인 반면 VR 장비 착용 후의 불안감은 2.0±1.21으로 불안도가 34%로 감소 한 것으로 나타났다. VR 장비에 대한 환자의 집중도가 검사에 대한 불안감에 미치는 영향력을 회귀분석 했을 때 B값은 0.750 (p<0.01), t값은 6.181 (p<0.01)으로 VR 장비에 집중할수록 검사 시 불안도가 감소하고 75%의 영향력이 있음을 나타냈다. 또한 전체적인 VR 장비에 대한 만족도는 3.76±1.28이었고 재사용의사율은 66%였다. 설문지의 신뢰도계수 Cronbach α값은 0.901로 나타났다. VR 장비를 사용할 경우 환자들의 주의가 분산되면서 불안감이 감소되고 심리적으로 안정되는 효과가 나타났다. 향후 VR 장비 기술이 발전됨에 따라 장비의 소형화가 가능해지고 VR 콘텐츠영상의 해상력이 증가하는 등 보다 사실적으로 환자에게 안정감이 제공된다면 임상에서도 다양하게 활용될 수 있을 것이라 사료된다.

• The Korean journal of internal medicine
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• 제33권6호
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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.

• 한국산업보건학회지
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• 제5권1호
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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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• 제24권4호
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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.

• 대한정형외과학회지
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• 제56권3호
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• pp.234-244
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• 2021

목적: 현재까지 군에서 발생하는 총기 및 폭발물 손상은 그 중요성에 비해 연구된 것이 제한적이었다. 이를 극복하기 위해 최근 4년간 총기 및 폭발물에 의해 수상한 군인 환자의 근골격계 손상에 대한 특징을 확인하고자 하였다. 대상 및 방법: 2015년 1월부터 2019년 7월까지 총기 및 폭발물에 의해 근골격계 손상을 당한 군인 환자를 대상으로 하였다. 의무 기록과 의료영상저장전송시스템 영상자료를 분석하고, 전화 면담을 통해 short musculoskeletal function assessment (SMFS)를 이용한 기능평가를 후향적으로 시행하였다. 기능평가에 대한 통계 분석으로 무기종류에 따른 분석은 t-test를, 다른 요인에 따른 분석은 ANOVA 분석을 실시하였다. 결과: 총기 및 폭발물에 의한 손상으로 치료받은 총 61명의 환자 중 30명(49.2%)이 근골격계 손상으로 정형외과적 치료를 시행받았다. 평균 수상 나이는 26.4세(21-52세)였다. 간부와 병사의 수는 비슷하였다. 총기 손상이 11명, 폭발물 손상이 19명이었다. 30명 중 수도병원에서 16명(53.3%)이, 민간병원에서 10명(33.3%)이 치료받았다. 12명에게 복수부위 손상이 있었고, 골절이 동반된 16명(53.3%)의 환자 중 절반 이상인 7명의 환자가 다발성 골절이었다. 수부와 하퇴부가 가장 흔한 수상 부위였다. 2명을 제외하고는 모두 개방창이 있었으며, 연부조직 재건술이 필요한 환자는 14명(46.7%)이었다. SMFS 기능평가에는 15명이 응답하였다. 계급에 따른 분석 결과, Borther Index에서 간부의 결과가 통계적으로 유의하게 낮은 것으로 분석되었다(p=0.05). 치료 병원에 따른 분석 결과, Dysfunction Index와 Bother Index 모두 수도병원에서 치료 받은 인원의 점수가 통계적으로 유의하게 낮은 것으로 분석되었다. (p=0.0008, p=0.0149) 결론: 국내 무기에 의해 수상한 군인 환자에 대해 분석한 첫 연구이다. 무기 손상 환자의 치료에 있어 orthopedic burden이 높음을 확인하였으며, 장기적으로 이런 환자들에 대한 치료평가 및 군 외상 시스템 발전을 위해 총기 및 폭발물에 의한 손상 환자를 포함한 군 외상환자 레지스트리 구축이 필요하겠다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.335-335
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• 2008

눈에 안정한(1.53um) 인산염 레이저 유리를 제조하기 위한 기본 조성 (mole%)은 $55P_2O_5\cdot24BaO\cdot10K_2O\cdot4Al_2O_3\cdot6Yb_2O_3$로 하고, 활성 이온은 $Er^{+3}$로, sensitizer로는 $Cr^{+3}(Yb^{+3})$을 사용하였다. 혼합된 원료 조성은 대기와 원료로부터 혼입되는 OH group을 제거하기 위하여 open 시스템에서 가스 버블을 공급하였으며, 용융물에 공급된 시간 변화에 따라 분광학적 특성 변화를 조사하였다. OH oscillations linear 에 의해 quenching된 $Er^{+3}$ 형광방출 확률은 $3500cm^{-1}$ 에서 OH stretching vibration band의 흡수계수에 의존하고 있으며, 이때 $Er^{+3}$의 농도는 $1.6\times10^{19}$에서 $21.2\times10^{19}$ ion/$cm^2$ 범위에서 존재하였다.

• Membrane and Water Treatment
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• 제9권1호
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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.