• Journal of Power Electronics
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• 제16권2호
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• pp.464-472
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• 2016

This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a single-phase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.

• 조명전기설비학회논문지
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• 제21권10호
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• pp.66-72
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• 2007

이 논문은 직류+60[Hz] 교류 중첩전압에서 신품과 노후된 18[kV] 산화아연 서지피뢰기의 누설전류와 전력손실에 대하여 기술하였다. 최대 50[kV]의 직류+60[Hz] 교류를 발생시킬 수 있는 중첩전압발생장치가 설계되고 제작되었다. 피뢰기의 I-V 특성곡선은 전압중첩률 K의 함수로 측정된다. DC와 AC 전압이 중첩된 I-V, R-V 특성곡선은 순수한 직류와 교류곡선 사이에 있고 저전류 영역에서 교차현상이 나타난다. 그 결과 중첩 전압에서 직류 성분의 증가는 ZnO 피뢰기의 전체 누설전류의 저항성분의 증가를 유발한다. 또한 같은 인가전압에서 피뢰기를 통해 흐르는 누설전류는 상용전원에서 장시간 스트레스 받은 피뢰기가 신품 피뢰기에 비해서 높게 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1588-1590
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• 2001

The voltage controlled ramp waveform(VCR) has recently been used in the reset period prior to addressing for plasma display. However, in this paper, the current controlled ramp waveform(CCR) which may prevent the oscillation of gap voltage cause current growth and decrease the background luminance has been suggested. As a result, in case of CCR method, the contrast ratio was about 14% increased compared with VCR method, whereas the addressing and sustainin discharge characteristics of CCR method were same with those of VCR method.

• 전기학회논문지P
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• 제67권1호
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• pp.1-8
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• 2018

ACL and DCL are have been conventionally used for reducing harmonic current on the input side of an ACMD. The current distortion ratio ITHD using ACL and DCL is only 35% to 85%, therefore to satisfy the IEEE Std. 519 requirements, the line filters has been focused as an alternative means. Those are installed between the AC power supply and the input of the ACMD, and must meet the IEEE Std. 519, be economical and be compact. To contribute to the widespread of using these line filters, we discussed concerning its topologies, simulation results, prototype test results as well as the cost evaluations. It included not only the proposed (NHHF) new hybrid harmonic filters which have both merits of simplicity and economic but also the past (BBHF) broadband harmonic filters and (HHF) hybrid harmonic filters.

• 전기학회논문지P
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• 제58권2호
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• pp.202-206
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• 2009

Evaluation system for calibrating Rogowski coiI(RC) up to primary current of 40,000 A have been established. The system consists of 40,000 A AC high current source, current transformer(CT) comparator, standard CT, RC under test, voltage to current convertor(VCC), buffer and CT burden. An AC high current is applied to the primary windings of both the standard CT and the RC under test, and then the CT comparator measures the ratio error and the phase displacement by comparing the secondary current of the standard CT with output current of VCC. For testing of RC, we have evaluated two RCs under test of primary current ranges of 0 A ${\sim}$ 2,000 A and 0 A ${\sim}$ 40,000 A with the accuracy class of 1 %. The extended uncertainty is 0.02 % ${\sim}$ 0.23 % for ratio error and 0.29 min ${\sim}$ 1.93 min for phase displacement in the primary current ranges of 10 ${\sim}$ 40,000 A.

• 대한수의학회지
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• 제51권2호
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• pp.151-158
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• 2011

The study evaluated whether a transgenic carrot vaccine could induce a K88-specific immune response in sows and whether the resultant maternal antibody could protect piglets against enterotoxigenic Escherichia coli (ETEC) K88ac infection. Sows (n = 15) selected randomly from a farm in Korea were assigned to three groups (n = 5 per group: control [untreated]), group A (orally inoculated with a nontransgenic and transgenic carrot vaccines at 2 and 4 weeks ante partum, respectively), and group B (conventionally vaccinated according to the manufacturer's instructions). After 7 days of lactation, 5 piglets selected randomly from each group were challenged with $1{\times}10^{10}$ colony forming units/mL ETEC K88ac. Group C had the lowest mean fecal consistency score on post-challenge days 1 and 7. Histiologically, On post-challenge day 7, group C showed an increased duodenum and ileum villus:crypt ratio, compared to group A in the duodenum, with group B displaying the highest ratio. Groups B and C had more increased villus width than group A in the jejunum. Group C displayed the greatest increase in villus width in the ileum. The colostrums and serum from groups B and C displayed higher concentrations of IgA and IgG against ETEC K88, compared to group A. Based on the results, it was concluded that the transgenic carrot vaccine in sow per oral may have an effect on preventing piglet diarrhea as good as commercial recombinant vaccine.

• Journal of Chest Surgery
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• 제50권3호
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• pp.163-170
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• 2017

Background: The absence of atrial contraction (AC) after the maze procedure has been reported to cause subsequent annular dilatation and to increase the risk of embolic stroke. We hypothesized that the lack of AC could increase the risk of permanent pacemaker (PPM) implantation in patients undergoing the maze procedure. Methods: In 376 consecutive patients who had undergone a cryo-maze procedure and combined valve operation, recovery of AC was assessed at baseline and at immediate (${\leq}2$ weeks), early (${\leq}1$ year, $4.6{\pm}3.8$ months), and late (>1 year, $3.5{\pm}1.1$ years) postoperative stages. Results: With a median follow-up of 53 months, 10 patients underwent PPM implantation. Seven PPM implants were for sinus node dysfunction (pauses of $9.6{\pm}2.4$ seconds), one was for marked sinus bradycardia, and two were for advanced/complete atrioventricular block. The median (interquartile range) time to PPM implantation was 13.8 (0.5-68.2) months. Our time-varying covariate Cox models showed that the absence of AC was a risk factor for PPM implantation (hazard ratio, 11.92; 95% confidence interval, 2.52 to 56.45; p=0.002). Conclusion: The absence of AC may be associated with a subsequent risk of PPM implantation.

• 핵의학기술
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• 제18권1호
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• pp.127-133
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• 2014

PET/CT에서 환자피폭 문제로 인해 저 선량의 중요성이 강조되고 있다. 본 연구에서는 기존에 사용되던 CT 데이터를 이용한 감쇠보정법인 CTAC와 새롭게 적용된 Q.AC를 환자실험과 팬텀 실험을 통해 저 선량으로 촬영 시 PET 영상에 미치는 영향에 대해 알아보고자 한다. 실험장비는 GE사의 PET/CT Discovery 710 (GE Healthcare, USA)를 사용하였으며 팬텀실험으로 감쇠보정의 정량적 평가를 위한 NEMA IEC body phantom과 균일성 평가를 위한 Uniform NU2-94 phantom을 사용하였다. 각각의 팬텀 내부에 동위원소 18-F FDG를 70.78 MBq, 22.2 MBq 주입하고 CT조건은 저 선량조건으로 80 kVp, 10 mA로부터 일반선량 조건으로 140 kVp, 120 mA 조건까지 스캔 후 CTAC와 Q.AC 두 감쇠보정법을 적용하여 재구성하였다. PET 영상에서 일반선량 조건을 기준값으로 정하고 horizomtal profile과 vertical profile을 통해 정량평가를 시행하고 기준값과의 상대적 오차를 평가하였다. 또한 환자실험으로 정상체중 환자와 과체중 환자를 구분하여 저 선량과 일반선량으로 비교 촬영한 뒤 CTAC와 Q.AC로 재구성된 PET영상에서 주요장기별 SUV에 대한 상대적 오차와 신호 대 잡음비를 비교분석하였다. 팬텀실험 결과 저선량 조건에서 CTAC와 Q.AC로 각각 재구성한 PET 영상의 profile과 상대적 오차에서 CTAC보다 Q.AC가 기준값과의 오차가 적은 그래프를 얻었다. 환자실험의 경우 일반선량 조건에서는 정상체중 환자와 과체중 환자 모두 감쇠보정법에 따른 상대적 오차값의 변화가 적었으나 저 선량 조건에서는 정상체중 환자보다 과체중 환자에서 감쇠보정법의 변경에 의한 상대적 오차의 감소폭이 커짐으로 기준값과 차이가 감소하였다. 기존의 감쇠보정법인 CTAC는 80 kVp, 10 mA의 저선량 CT를 사용하는데 있어 PET 영상의 선속경화현상이 발생한다. 이로 인해 CTAC를 이용하여 재구성된 PET 데이터는 정량화하는데 문제가 될 수 있음을 확인했다. 반면에 새로운 알고리즘이 적용된 Q.AC는 과체중 환자의 경우 80 kVp, 10 mA 정도까지는 140 kVp, 120 mA 조건으로 촬영하여 재구성한 PET 데이터 결과와 차이가 적음을 확인할 수 있었다. Q.AC를 이용한 경우 기존보다 저 선량의 CT를 이용해 PET의 재구성에 이용할 수 있으므로 환자의 피폭을 줄이는 데 큰 역할을 할 것으로 기대한다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8265-8270
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• 2016

Purpose: A cost-utility analysis was performed to assess the cost-utility of neoadjuvant chemotherapy regimens containing doxorubicin and cyclophosphamide (AC) versus paclitaxel and gemcitabine (PG) for locally advanced breast cancer patients in Iran. Materials and Methods: This cross-sectional study in Namazi hospital in Shiraz, in the south of Iran covered 64 breast cancer patients. According to the random numbers, the patients were divided into two groups, 32 receiving AC and 32 PG. Costs were identified and measured from a community perspective. These items included medical and non-medical direct and indirect costs. In this study, a data collection form was used. To assess the utility of the two regimens, the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core30 (EORTC QLQ-C30) was applied. Using a decision tree, we calculated the expected costs and quality adjusted life years (QALYs) for both methods; also, the incremental cost-effectiveness ratio was assessed. Results: The results of the decision tree showed that in the AC arm, the expected cost was 39,170 US$ and the expected QALY was 3.39 and in the PG arm, the expected cost was 43,336 dollars and the expected QALY was 2.64. Sensitivity analysis showed the cost effectiveness of the AC and ICER=-5535 US$. Conclusions: Overall, the results showed that AC to be superior to PG in treatment of patients with breast cancer, being less costly and more effective.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.4123-4126
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• 2015

Background: Carcinoma of the esophagus is associated with significant morbidity and mortality. The most common subtype is squamous cell carcinoma (SCC). In the past three decades, the incidence of SCC has been reported to be decreasing whereas esophageal adenocarcinoma (AC) is increasing. This study assessed the trend of esophageal cancer in Brunei Darussalam over a three decades period. Materials and Methods: The National Cancer registry was searched for esophageal cancers from 1986 to 2012. Data on age, gender, racial groups (Malays, Chinese, Indigenous and foreign nationals) and histology type were collected. The rate (ASR) and Age Specific Incidence rate (ASIR) were calculated. Results: The predominant tumor type was SCC which accounted for 89% of all esophageal cancer. The gender ratio was 2.25: 1 (male: female) and the mean age at diagnosis was $66.9{\pm}12.9$ years, significantly younger for esophageal AC ($57.2{\pm}16.0$) compared to SCC ($68.1{\pm}12.0$, p<0.05), and among the foreign nationals (p<0.05 for trend). The proportions of SCC among all esophageal cancers in the various racial groups were: Malays (87.8%), Chinese (100%), Indigenous (100%) and foreign nationals (20%). None of the Chinese and Indigenous groups were diagnosed with esophageal AC. The overall ASR for esophageal cancer was 2.1/100,000; 2.0/100,000 for SCC with a declining trend and 0.17/100,000 for esophageal AC, without any trend observed. Among the two major racial groups; the Chinese has higher ASR (3.42/100,000) compared to the Malays (ASR 0.95/100,000). Conclusions: SCC is the predominant tumor type of esophageal cancer in Brunei Darussalam and more common among the Chinese. There was a declining trend in the incidence of SCC but not for esophageal AC.