• 한국의학물리학회지:의학물리
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• 제34권4호
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• pp.48-54
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• 2023

Purpose: In this study, the dosimetric characteristics of lung stereotactic body radiotherapy (SBRT) plans using the new Halcyon system were analyzed to assess its suitability. Methods: We compared the key dosimetric parameters calculated for the Halcyon SBRT plans with those of a conventional C-arm linear accelerator (LINAC) equipped with a high-definition multileaf collimator (HD-MLC)-Trilogy Tx. A total of 10 patients with non-small-cell lung cancer were selected, and all SBRT plans were generated using the RapidArc technique. Results: Trilogy Tx exhibited significant superiority over Halcyon in terms of target dose coverage (conformity index, homogeneity index, D_{0.1 cc}, and D_95%) and dose spillage (gradient). Trilogy Tx was more efficient than Halcyon in the lung SBRT beam delivery process in terms of the total number of monitor units, modulation factor, and beam-on time. However, it was feasible to achieve a dose distribution that met SBRT plan requirements using Halcyon, with no significant differences in satisfying organs at risk dose constraints between both plans. Conclusions: Results confirm that Halcyon is a viable alternative for performing lung SBRT in the absence of a LINAC equipped with HD-MLC. However, extra consideration should be taken in determining whether to use Halcyon when the planning target volume setting is enormous, as in the case of significant tumor motions.

• 대한전자공학회논문지
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• 제26권3호
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• pp.145-152
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• 1989

두께가 5${mu}m$인 Agfa 8E75 HD 필름에 He-Ne 레이저를 사용하여 고효율 회절격자를 형성하였다. 은염에 기록된 격자의 회절효율은 물질자체에 의해 제한되기 보다는 화학적 처리 과정에 많이 좌우된다. 특히 중크롬산 칼륨 표백액과 알코올 건조를 이용하여 노출량 180${mu}J/cm^2$에서 71%(두 경계면에서의 반사량을 고려하면 81%)의 회절효율을 얻었다. 중크롬산에 의한 연계결합과 급속 건조에 의한 공기 간격이 굴절율 변조도를 증가시켰다. 알코올 건조에 의해 감광유제가 부풀어 올라 기록 각도보다 큰 각에서 Bragg 조건이 일어나고 이를 전자 현미경 사진을 통해 밝혔으며, 결과적으로 두께의 제어가 고효율을 위한 잠재적 원천으로 작용함을 알 수 있었다.

• Journal of Power Electronics
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• 제18권2호
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• pp.547-557
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• 2018

This work proposes a control method of frequency stabilization for grid integration of large-scale wind farms via the voltage source converter-based high-voltage direct current (VSC-HVDC) technology. First, the topology of grid integration of a large-scale wind farm via the VSC-HVDC link is provided, and simple control strategies for wind turbines, wind farm side VSC (WFVSC), and grid side VSC are presented. Second, a mathematical model between the phase angle of WFVSC and the frequency of the wind farm is established. The control principle of the large-scale wind power integrated system is analyzed in theory in accordance with the mathematical model. Third, frequency and AC voltage controllers of WFVSC are designed based on the mathematical model of the relationships between the phase angle of WFVSC and the frequency of the wind farm, and between the modulation index of WFVSC and the voltage of the wind farm. Corresponding controller structures are established by deriving a transfer function, and an optimization method for selecting the parameters of the frequency controller is presented. Finally, a case study is performed under different operating conditions by using the DIgSILENT/PowerFactory software. Results show that the proposed control method has good performance in the frequency stabilization of the large-scale wind power integrated system via the VSC-HVDC technology.

• 한국광학회지
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• 제26권4호
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• pp.203-208
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• 2015

파장 투과 대역폭이 좁으면서도 반사율이 높은 파장 필터를 구현하기 위해서 격자의 반사율이 진행 방향을 따라 서서히 변하는 구조의 에포다이즈드 격자 구조를 폴리머 광도파로와 함께 제작하였다. 격자로 인한 유효 굴절률 변화가 $5{\times}10^{-4}$인 경우에 대하여 에포다이즈드 격자의 길이에 따른 반사율 변화를 설계하였으며 길이가 15 mm 이상이 되는 경우에 반사율이 99%에 도달함을 확인하였다. 길이가 서로 다른 여러 개의 격자를 제작하여 반사율, 3-dB 대역폭, 20-dB 대역폭을 측정하였으며, 격자 길이가 18 mm인 소자에서 95%의 반사율을 얻을 수 있었고, 이때 3-dB 대역폭은 0.28 nm, 그리고 20-dB 대역폭은 0.70 nm의 특성을 가짐을 확인하였다.

• Nutrition Research and Practice
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• 제7권6호
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• pp.430-438
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• 2013

Increased oxidative stress in obese diabetes may have causal effects on diabetic complications, including dyslipidemia. Lipopolysccharides (LPS) along with an atherogenic diet have been found to increase oxidative stress and insulin resistance. Cranberry has been recognized as having beneficial effects on diseases related to oxidative stress. Therefore, we employed obese diabetic animals treated with an atherogenic diet and LPS, with the aim of examining the effects of cranberry powder (CP) on diabetic related metabolic conditions, including lipid profiles, serum insulin and glucose, and biomarkers of oxidative stress. Forty C57BL/KsJ-db/db mice were divided into the following five groups: normal diet + saline, atherogenic diet + saline, atherogenic diet + LPS, atherogenic diet + 5% CP + LPS, and atherogenic diet + 10% CP + LPS. Consumption of an atherogenic diet resulted in elevation of serum total cholesterol and atherogenic index (AI) and reduction of high density lipoprotein (HDL)-cholesterol. However, with 10% CP, the increase in mean HDL-cholesterol level was close to that of the group with a normal diet, whereas AI was maintained at a higher level than that of the group with a normal diet. LPS induced elevated serum insulin level was lowered by greater than 60% with CP (P < 0.05), and mean serum glucose level was reduced by approximately 19% with 5% CP (P > 0.05). Mean activity of liver cytosolic glutathione peroxidase was significantly increased by LPS injection, however it was reduced back to the value without LPS when the diet was fortified with 10% CP (P < 0.05). In groups with CP, a reduction in mean levels of serum protein carbonyl tended to occur in a dose dependent manner. Particularly with 10% CP, a reduction of approximately 89% was observed (P > 0.05). Overall results suggest that fortification of the atherogenic diet with CP may have potential health benefits for obese diabetes with high oxidative stress, by modulation of physical conditions, including some biomarkers of oxidative stress.

• 한국축산식품학회지
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• 제34권6호
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• pp.829-835
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• 2014

Inflammatory bowel disease (IBD) is caused by dysregulation of colon mucosal immunity and mucosal epithelial barrier function. Recent studies have reported that lipoteichoic acid (LTA) from Lactobacillus plantarum K8 reduces excessive production of pro-inflammatory cytokine. In this study, we investigated the preventive effects of lysate of Lb. plantarum K8 in dextran sulfate sodium (DSS)-induced colitis. Male Sprague-Dawley rats were orally pretreated with lysate of Lb. plantarum K8 (low dose or high dose) or live Lb. plantarum K8 prior to the induction of colitis using 4% DSS. Disease progression was monitored by assessment of disease activity index (DAI). Histological changes of colonic tissues were evaluated by hematoxylin and eosin (HE) staining. Tumor necrosis factor-alpha (TNF-${\alpha}$), interleukin-6 (IL-6) levels were measured using enzyme-linked immunosorbent assay (ELISA). The colon mRNA expressions of TNF-${\alpha}$, IL-6, and toll like receptor-2 (TLR-2) were examined by quantitative real-time-transcription polymerase chain reaction (qPCR). Lysate of Lb. plantarum K8 suppressed colon shortening, edema, mucosal damage, and the loss of DSS-induced crypts. The groups that received lysate of Lb. plantarum K8 exhibited significantly decreased levels of the pro-inflammatory cytokines TNF-${\alpha}$ and IL-6 in the colon. Interestingly, colonic expression of toll like receptor-2 mRNA in the high-dose lysate of Lb. plantarum K8 group increased significantly. Our study demonstrates the protective effects of oral lysate of Lb. plantarum K8 administration on DSS-induced colitis via the modulation of pro-inflammatory mediators of the mucosal immune system.

• 대한약침학회지
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• 제19권3호
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• pp.207-212
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• 2016

Objectives: Acupuncture treatments are safe and effective for a wide variety of diseases involving autonomic dysregulation. Heart rate variability (HRV) is a noninvasive method for assessing sympathovagal balance. The low frequency/high frequency (LF/HF) spectral power ratio is an index of sympathovagal influence on heart rate and of cardiovascular health. This study tests the hypothesis that from rest to 30% to 50% of peak oxygen consumption, the nonlinear Conte-Zbilut-Federici (CZF) method of computing the LF/HF ratio is a more reliable index of changes in the HRV than linear methods are. Methods: The subjects of this study were 10 healthy young adults. Electrocardiogram RR intervals were measured during 6-minute periods of rest and aerobic exercise on a cycle ergometer at 30% and 50% of peak oxygen consumption ($VO_{2peak}$). Results: The frequency domain CZF computations of the LF/HF ratio and the time domain computations of the standard deviation of normal-to-normal intervals (SDNN) decreased sequentially from rest to 30% $VO_{2peak}$ (P < 0.001) to 50% $VO_{2peak}$ (P < 0.05). The SDNN and the CZF computations of the LF/HF ratio were positively correlated (Pearson's r = 0.75, P < 0.001). fast Fourier transform (FFT), autoregressive (AR) and Lomb periodogram computations of the LF/HF ratio increased only from rest to 50% $VO_{2peak}$. Conclusion: Computations of the LF/HF ratio by using the nonlinear CZF method appear to be more sensitive to changes in physical activity than computations of the LF/HF ratio by using linear methods. Future studies should determine whether the CZF computation of the LF/HF ratio improves evaluations of pharmacopuncture and other treatment modalities.

• 한국소프트웨어감정평가학회 논문지
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• 제16권1호
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• pp.55-63
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• 2020

광대역 광통신 시스템에 사용되는 레이저는 우수한 주파수 선택성과 모드 안정성을 가져야한다. DFB(Distributed Feedback) 레이저는 고주파로 전류 변조를 하더라도 발진 주파수의 변화가 적다. 본 연구에서는 1.55um의 파장을 갖는 DFB 레이저에서 굴절률 격자와 이득 격자가 동시에 존재할 때, 오른쪽 거울 면에 반사가 일어나지 않도록 유전막 코팅을 하여 ρ_r=0 이 되도록 하였다. 문턱에서 최소 이득을 필요로 하는 제 1모드에 대하여, 종 방향으로의 발진 모드의 빔 분포와 방사전력비 P_l/P_r를 ρ_l의 위상=π인 경우와 ρ_l의 위상=π/2인 경우에 대하여 비교 검증했다. ρ_l의 위상=π인 경우, 낮은 문턱 전류와 높은 주파수 안정성을 얻기 위해서는, κL이 8보다 커야 한다. ρ_l의 위상=π/2인 경우, 낮은 문턱 전류를 위해서는 κL=1.0이 되도록 해야 하고, 이때 발진 주파수는 격자 주파수와 일치한다. 반사 방지 코팅을 하지 않은, 두 개의 거울 면을 가진 1.55um의 파장을 갖는 DFB 레이저보다, 한쪽 거울 면에 무반사 코팅을 한 경우에 모드 선별성이 훨씬 크다.

• 한국조명전기설비학회지:조명전기설비
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• 제7권3호
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• pp.27-33
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• 1993

본 논문은 캐리어 주파수 20kHz 이상의 고주파 전압형 PWM 인버터를 구동하기 위한 디지털 제어기에 관한 연구이다.적절한 PWM 패턴을 선택하기 위하여 기존의 PWM을 분석하였고, 비동기형 계단 정현파를 기준신호로 하여 제어기의 PWM 패턴을 구하였으며, PWM 제어방법은 가변 캐리어 비를 이용하였다.PWM 제어기는 모두 디지털 방식으로 구성하였다. 특히, 제시된 제어기의 구성은 연산 및 데이터 처리와 PWM 패턴 합성을 8비트 원칩 마이크로프로세서와 디지털 로직으로 나누어 설계하므로써 제어에 대한 속응성 및 제어성을 개선하였다. 또 변조도 데이터를 9비트로 출력하도록 프로그램을 적절히 이용하여 데이터 처리능력을 높였다.디지털 제어기는 회로구성을 i8051과 원칩 EPLD로 구성하였고, 설계된 제어기는 전압형 인버터를 동작시켜 제어성을 고찰하였다. 그리고 전압형 인버터 시스템의 고조파와 전류파형을 평가 분석하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제18권3호
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• pp.269-278
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• 2014

Various antiepileptic drugs (AEDs) especially enzyme-inducing AEDs might be associated with increased vascular risk, through impairment of the endogenous antioxidative ability which may trigger oxygen-dependent tissue injury. Lamotrigine (LTG) a non-enzyme-inducing AED has scarce information regarding its effects on oxidative stress. The present study aimed to study the possible modulation of vascular risk factors of epileptogenesis by LTG, in a rat model of kindling seizure induced by pentylenetetrazole (PTZ). Four groups of male Wister rats were used; vehicle control group, PTZ group (alternate day PTZ, 30 mg/kg, i.p), LTG/PTZ group (LTG 20 mg/kg/day p.o and alternate day PTZ) and LTG group. The study period was 5 weeks. Lipoproteins and total homocysteine (tHcy), malondialdehyde (MDA) and reduced glutathione (GSH) were measured. Aortic endothelial function study and histopathological examination of the rats' brains, aortas and coronaries were conducted. Serum total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C), tHcy, MDA, GSH levels were significantly higher in epileptic rats than normal controls rats. A decrease in HDL-cholesterol with high atherosclerotic index was also demonstrated. The administration of LTG improved the PTZ-kindled seizures. It produced a significant decrease in TC, TG and LDL-cholesterol, MDA, aortic GSH and increase in HDL-cholesterol with no significant effect on serum GSH and tHcy levels. LTG improved endothelium-dependent relaxation, decreased hippocampal neurodegenerative changes and atherosclerotic changes of aortas and coronaries. LTG decreased seizures severity, hippocampal damage and improved vascular risk markers in this rat model of kindling seizures.