DAB Converter Based on Unified High-Frequency Bipolar Buck-Boost Theory for Low Current Stress

Kan, Jia-rong,Yang, Yao-dong,Tang, Yu,Wu, Dong-chun,Wu, Yun-ya,Wu, Jiang The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

This paper proposes a unified high-frequency bipolar buck-boost (UHFBB) control strategy for a dual-active-bridge (DAB), which is derived from the classical buck and boost DC/DC converter. It can achieve optimized current stress of the switches and soft switching in wider range. The UHFBB control strategy includes multi-control-variables, which can be achieved according to an algorithm derived from an accurate mathematical model. The design method for the parameters, such as the transformer turns ratio and the inductance, are shown. The current stress of the switches is analyzed for selecting an optimal inductor. The analysis is verified by the experimental results within a 500W prototype.

Short-course palliative radiotherapy for uterine cervical cancer

Dong Hyun Kim,Ju Hye Lee,Yong Kan Ki,Ji Ho Nam,Won Taek Kim,Ho Sang Jeon,Dahl Park,Dong Won Kim 대한방사선종양학회 2013 Radiation Oncology Journal Vol.31 No.4

Purpose: The purpose of this retrospective study was to evaluate the efficacy and feasibility of short-course hypofractionated radiotherapy (RT) for the palliation of uterine cervical cancer. Materials and Methods: Seventeen patients with cancer of the uterine cervix, who underwent palliative hypofractionated 3-dimensional conformal radiotherapy between January 2002 and June 2012, were retrospectively analyzed. RT was delivered to symptomatic lesions (both the primary mass and/or metastatic regional lymph nodes). The total dose was 20 to 25 Gy (median, 25 Gy) in 5 Gy daily fractions. Results: The median follow-up duration was 12.2 months (range, 4 to 24 months). The median survival time was 7.8 months (range, 4 to 24 months). Vaginal bleeding was the most common presenting symptom followed by pelvic pain (9 patients). The overall response rates were 93.8% and 66.7% for vaginal bleeding control and pelvic pain, respectively. Nine patients did not have any acute side effects and 7 patients showed minor gastrointestinal toxicity. Only 1 patient had grade 3 diarrhea 1 week after completion of treatment, which was successfully treated conservatively. Late complications occurred in 4 patients; however, none of these were of grade 3 or higher severity. Conclusion: Short-course hypofractionated RT was effective and well tolerated as palliative treatment for uterine cervical cancer.

Short-course palliative radiotherapy for uterine cervical cancer

Kim, Dong Hyun,Lee, Ju Hye,Ki, Yong Kan,Nam, Ji Ho,Kim, Won Taek,Jeon, Ho Sang,Park, Dahl,Kim, Dong Won The Korean Society for Radiation Oncology 2013 Radiation Oncology Journal Vol.31 No.4

Purpose: The purpose of this retrospective study was to evaluate the efficacy and feasibility of short-course hypofractionated radiotherapy (RT) for the palliation of uterine cervical cancer. Materials and Methods: Seventeen patients with cancer of the uterine cervix, who underwent palliative hypofractionated 3-dimensional conformal radiotherapy between January 2002 and June 2012, were retrospectively analyzed. RT was delivered to symptomatic lesions (both the primary mass and/or metastatic regional lymph nodes). The total dose was 20 to 25 Gy (median, 25 Gy) in 5 Gy daily fractions. Results: The median follow-up duration was 12.2 months (range, 4 to 24 months). The median survival time was 7.8 months (range, 4 to 24 months). Vaginal bleeding was the most common presenting symptom followed by pelvic pain (9 patients). The overall response rates were 93.8% and 66.7% for vaginal bleeding control and pelvic pain, respectively. Nine patients did not have any acute side effects and 7 patients showed minor gastrointestinal toxicity. Only 1 patient had grade 3 diarrhea 1 week after completion of treatment, which was successfully treated conservatively. Late complications occurred in 4 patients; however, none of these were of grade 3 or higher severity. Conclusion: Short-course hypofractionated RT was effective and well tolerated as palliative treatment for uterine cervical cancer.

DAB Converter Based on Unified High-Frequency Bipolar Buck-Boost Theory for Low Current Stress

Jia-rong Kan,Yao-dong Yang,Yu Tang,Dong-chun Wu,Yun-ya Wu,Jiang Wu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

This paper proposes a unified high-frequency bipolar buck-boost (UHFBB) control strategy for a dual-active-bridge (DAB), which is derived from the classical buck and boost DC/DC converter. It can achieve optimized current stress of the switches and soft switching in wider range. The UHFBB control strategy includes multi-control-variables, which can be achieved according to an algorithm derived from an accurate mathematical model. The design method for the parameters, such as the transformer turns ratio and the inductance, are shown. The current stress of the switches is analyzed for selecting an optimal inductor. The analysis is verified by the experimental results within a 500W prototype.

전방십자인대 손상 유무와 대퇴 과간 절흔의 형상과의 상관관계 비교

김형간(Hyung Kan Kim),문동규(Dong Kyu Moon),곽지용(Ji Yong Gwark),남대철(Dae Cheol Nam),김동희(Dong Hee Kim),황선철(Sun Chul Hwang) 대한정형외과학회 2013 대한정형외과학회지 Vol.48 No.6

목적: 슬관절 자기공명영상을 이용하여 과간 절흔의 모양과 폭, 부피를 측정하여 전방십자인대 손상의 유무에 따른 각각의 측정값 사이의 상관관계를 알아보고자 하였다. 대상 및 방법: 전방십자인대 손상군 72명, 비손상군 80명의 자기공명영상을 이용하여 관간절흔의 삼차원적인 부피와 이차원적인 폭과 모양을 측정하여, 전방십자인대 손상군과 비손상군으로 나누어 비교하였다. 과간 절흔의 폭, 모양, 부피 간의 상관관계를 분석하였고, 관찰자 간, 관찰자 내의 신뢰성을 확인하였다. 결과: 성별에 관계 없이 전방십자인대 손상군에서 과간 절흔의 폭이 더 작았고 통계적으로 유의한 차이를 보였다(p<0.001). 과간 절흔의 부피는 전방십자인대 손상군에서 비손상군보다 더 작았으나 통계적으로 유의한 차이는 없었다(남: p=0.43, 여: p=0.22). 전방십자인대 손상군과 정상군 간에 과간 절흔 모양의 차이는 없었다(남: p=0.16, 여: p=0.88). 결론: 과간 절흔의 폭은 전방십자인대 손상의 위험을 예측하는 데 좋은 지표로 이용할 수 있으나 과간 절흔의 모양과 부피는 전방십자인대 손상의 위험을 판단하는 지표로서 의미가 없다. Purpose: The aim of this study was to evaluate the correlation between the 3-dimensional (D) notch volume and the 2D notch width and notch shape as measured on magnetic resonance imaging (MRI), between subjects with anterior cruciate ligament (ACL) injury and those without ACL injury. Materials and Methods: Knee MRI images were taken from 72 subjects with ACL injury and 80 subjects without ACL injury (January 2007 to January 2012; Gyeongsang National University Hospital, Jinju, Korea). We measured 3D notch volume and 2D notch width and notch shape. The measured values from MRI figures between ACL-injured subjects and non-ACL-injured subjects were compared and analyzed. These measurements (notch width, notch ratio) were correlated to notch volume. Both intra-observer reliability and inter-observer reliability were calculated. Results: Notch width differed significantly between ACL injured subjects and non-injured subjects (p<0.001), while no significant differences in notch volume and notch shape were observed between the groups (male: p=0.43, female: p=0.22). Conclusion: The results of this study might suggest that certain 2D measurements (notch width) of the notch could be better than notch volume for prediction of ACL rupture risk.

조기 성문암의 방사선치료에서 경동맥을 보호하기 위한 치료 계획

기용간(Yong Kan Ki),김원택(Won Taek Kim),남지호(Ji Ho Nam),김동현(Dong Hyun Kim),이주혜(Ju Hye Lee),박달(Dal Park),김동원(Dong Won Kim) 대한방사선종양학회 2011 Radiation Oncology Journal Vol.29 No.2

목적: 조기 성문암 환자에서 방사선치료의 만기 합병증인 뇌졸증을 예방하기 위해 경동맥을 보호하는 치료계획을 세우고 타당성을 알아보고자 연구를 계획하였다. 대상 및 방법: 2007년 1월부터 2010년 12월까지 원발성 조기 성문암으로 방사선치료를 받은 환자 중 전산화단층촬영모의치료를 받은 환자 31명의 모의치료 영상을 대상으로 하였다. 기존의 평행대항조사영역(parallel-opposing field, POF)과 조사영역의 빔방향상에서 동측의 경동맥을 제외하기 위해 빔각도를 조절한 조사영역(modified oblique field, MOF)으로 가상모의치료계획을 세우고 계획용표적체적, 경동맥과 척수의 선량분포, 평균선량과 V₃₅, V₄₀, V₅₀ 등을 기존 치료와 비교 분석하였다. 결과: 전체 31명 중 23명(74.2%)에서 25도, 8명(25.8%)에서 30도 전방으로 조절되었다. 두 군 사이에 선량에 따른 planning target volume의 체적백분율은 차이를 보이지 않았다(p=0.801). 경동맥의 선량에 따른 누적 체적백분율은 의미 있는 차이를 보였고(p<0.001), 26 ㏉ 이후에 MOF군에서 감소하기 시작했다. 경동맥의 평균선량은 POF군에서 38.5 ㏉, MOF군에서 26.3 ㏉였고(p=0.012), V₃₅, V₄₀, V₅₀ 모두에서 의미 있는 차이를 보였다. 결론: 이번 연구 결과로 조기 성문암 환자에서 빔각도를 전방으로 조절하여 경동맥의 조사선량을 감소시켰다. 이를 통해 경동맥 협착증을 예방하고 궁극적으로 뇌졸증을 줄일 수 있을 것으로 예상한다. Purpose: To examine the feasibility of the treatment planning for minimizing carotid artery dose in the radiotherapy of early glottic cancer. Materials and Methods: From 2007 to 2010, computed tomography simulation images of 31 patients treated by radiotherapy for early glottic cancer were analyzed. The virtual planning was used to compare the parallel-opposing fields (POF) with the modified oblique fields (MOF) placed at angles to exclude the ipsilateral carotid arteries. Planning target volume (PTV), irradiated volume, carotid artery, and spinal cord were analyzed at a mean dose, V₃₅, V₄₀, V₅₀ and with a percent dose-volume. Results: The beam angles were arranged 25 degrees anteriorly in 23 patients and 30 degrees anteriorly in 8 patients. The percent dose-volume of PTV shows no statistical difference. Conversely, the cumulative percent dose-volume of carotid artery shows the significant difference (p<0.001). The mean doses of carotid artery were 38.5 ㏉ for POF and 26.3 ㏉ for MOF and the difference was statistically significant (p=0.012). Similarly, V₃₅, V₄₀, and V₅₀ also showed significant differences between POF and MOF. Conclusion: The modified oblique field was respected to prevent a carotid artery stenosis and reduce the incidence of a stroke based on these results.

Comparison of Three Active-Frequency-Drift Islanding Detection Methods for Single-Phase Grid-Connected Inverters

Kan, Jia-rong,Jiang, Hui,Tang, Yu,Wu, Dong-chun,Wu, Yun-ya,Wu, Jiang The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

A novel islanding detection method is proposed in this paper. It is based on a frequency drooping PLL, which was presented in a previous work. The cause of errors in the non-detection zone (NDZ) of conventional frequency disturbance islanding detection methods (IDM) is analyzed. A frequency drooping phase-locked-loop (FD-PLL) is introduced into a single-phase grid-connected inverter (SPGCI), which can guarantee that grid current is in phase with the grid voltage. A novel FD-PLL IDM is proposed by improving this PLL. In order to verify the performance of the proposed FD-PLL IDM, a full performance comparison between the proposed IDM and typical existing active frequency drift IDMs is carried out, which includes both dynamic performance and steady performance. With the same NDZ, the total harmonic distortion of the grid-current in the dynamic process and steady state is analyzed. The proposed FD-PLL IDM, regardless of the dynamic or steady process, has the best power quality. Experimental and simulation results verify that the proposed FD-PLL IDM has excellent performance.

Research Progress in SiC-Based Ceramic Matrix Composites

Dong, Shaoming,Wang, Zhen,Zhou, Haijun,Kan, Yan-Mei,Zhang, Xiangyu,Ding, Yusheng,Gao, Le,Wu, Bin,Hu, Jianbao The Korean Ceramic Society 2012 한국세라믹학회지 Vol.49 No.4

SiC-based ceramic matrix composites show many advantages over their monolithic ceramic counterparts, which makes them potential candidates for applications in various fields. Depending strongly on the chemical composition and microstructure of the fiber reinforcement, matrix as well as the fiber/matrix interphase in the material, the properties of ceramic matrix composites(CMCs) are highly tailorable. In this paper, the latest progresses in the interphase design, matrix modification and fiber reinforcement decoration of CMCs are reviewed, their effects on the properties of the CMCs are introduced.

Bandgap opening in few-layered monoclinic MoTe2

Keum, Dong Hoon,Cho, Suyeon,Kim, Jung Ho,Choe, Duk-Hyun,Sung, Ha-Jun,Kan, Min,Kang, Haeyong,Hwang, Jae-Yeol,Kim, Sung Wng,Yang, Heejun,Chang, K. J.,Lee, Young Hee Nature Publishing Group 2015 Nature physics Vol.11 No.6

Effect of multi-walled carbon nanotube dispersion on the electrical and rheological properties of poly(propylene carbonate)/poly(lactic acid)/multi-walled carbon nanotube composites

Park, Dong Hyup,Kan, Tae Gyu,Lee, Yun Kyun,Kim, Woo Nyon Springer-Verlag 2013 JOURNAL OF MATERIALS SCIENCE - Vol.48 No.1