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정현추종 제어기를 이용한 전압형 PWM 컨버터의 입력전류제어
우정인,정기화,최선영,허태원 東亞大學校 附設 情報通信硏究所 1999 情報通信硏究所論文誌 Vol.7 No.1
This paper presents the sinusoidal tracking controllr in order to eliminate the steady state control error and to improve the transient characteristics for input current in voltage source PWN congerter. A general mathematical model with switching functions of the PWM converter that is represented as differential equation is established. The proposed model in current control system that does not require coordinate transformations is described. It is proved that the steady state deviation reduces to zero from a transfer function of input current control system. The sinusoidal tracking controller is realized by differential equations for the LC equivalent circuit. From simulations and experimental work, it is verified that the control system can eliminate the steady state error of input current and also improve the transient state characteristic.
Hwa-Sun Kim(김화선),Jae-Hwan Cho(조재환),Young-Joon Park(박영준),Yeong-Cheol Heo(허영철) 한국자기학회 2018 韓國磁氣學會誌 Vol.28 No.4
The purpose of this study was to aid in the diagnosis of knee synovial hypertrophy using DIR sequences without contrast agents. In the 3.0T MR system, the TI value was set to TI1/TI2 (2805/229 msec) and applied to the DIR technique. At this time, no contrast agent was used. In synovium and effusion, DIR showed higher SNR and CNR than T2WI and PDWI. In conclusion, the DIR technique using the proposed TI value is useful for the diagnosis of knee synovial hypertrophy as compared with the conventional image. In the future, this study will provide basic data in the study applying DIR technique to various diseases.
Effect of HPLC Analytical Procedure upon Determining Drug Content in PLGA Microspheres
Heo, Sun-Ju,Lee, Hong-Hwa,Lee, Min-Jung,Sah, Hong-Kee The Korean Society of Pharmaceutical Sciences and 2010 Journal of Pharmaceutical Investigation Vol.40 No.3
The objective of this study was to investigate the effects of sample preparation, HPLC conditions and peak measurement methods upon determining progesterone content of poly-d,l-lactide-co-glycolide microspheres. A series of the microspheres with different formulations was first prepared. To determine their actual drug contents, the microspheres were dissolved in tetrahydrofuran and diluted with various amounts of methanol to precipitate the polymer. After removal of polymeric precipitates, the filtrates were subject to HPLC analysis under versatile experimental conditions. Interestingly, the composition of a sample solution (e.g., the ratio of methanol to tetrahydrofuran) affected the magnitudes of both peak fronting and peak broadening of progesterone. Its peak became broader and more asymmetrical at lower methanol:tetrahydrofuran ratios. Furthermore, its peak height was influenced by the proportion of tetrahydrofuran in a sample solution. Such problems encountered with tetrahydrofuran were exacerbated when a larger volume of the sample solution was injected onto an analytical column. Under our experimental conditions a peak area measurement provided more accurate and reliable determination of progesterone content in various microspheres than a peak height determination. Optimizing the composition of a sample solution, HPLC chromatographic conditions and peak analysis methods was a prerequisite to an accurate determination of progesterone encapsulated within microspheres.
허경화,한영선,정혜선,구정완 大韓産業醫學會 2004 대한직업환경의학회지 Vol.16 No.1
목적: 직업관련성 근골격계질환과 관련된 여러 가지 위험요인에 노출되어 있는 경기보조원의 작업내용과 관련하여 근골격계 증상 유발 양상을 파악하고, 근골격계 증상 관련 요인을 파악하고자 하였다. 방법: 경기도 지역에 있는 6개 정규 골프장을 대상으로 경기보조원 316명에 대하여 2003년 4월 9일부터 4월 30일까지 3주간 설문지를 배부한 후 자기 기입 식으로 작성하게 하여 수거함으로써 자각증상 조사를 실시하였으며, 설문지는 미국 산업안전보건연구원이 사용하는 표준화된 설문지(NIOSH, 1993)의 국내 번역판(노상철 등, 1997)을 이용하였다. 결과: 조사대상 경기보조원의 신체 부위별 근골격계 자각증상 호소율은 다리/무릎/발목/발이 41.8%로 가장 높은 증상 호소율을 보였으며 어깨 35.8%, 등/허리 35.8%, 목 28.8%, 팔/손목/손가락 28.5% 순 이었다. 성수기의 1일 근무시간이 팔/손목/손가락 부위를 제외한 나머지 부위에 영향을 주는 것으로 나타났다. 경기보조원의 업무특성과 관련하여 골프장의 경사와 굴곡의 정도, 내장객의 폭언 및 폭행, 업무의 속도를 조절할 수 없음, 일의 육체적 부담의 강도, 고용의 불안정성, 직장을 잃을 가능성 등이 근골격계 자각증상과 유의한 연관성을 보였다. 직무스트레스 특성에서는 정신적 직무요구도가 높은 반면, 낮은 직무 재량도를 보여 근무긴장도가 높은 것으로 조사되었다. 다변량 로지스틱 회귀분석을 실시한 결과 목 부위, 어깨 부위, 등/허리 부위 및 다리/무릎/발목/발 부위의 근골결계 증상에는 성수기 12시간 이상의 근무시간이, 팔/손목/손가락 부위의 증상에는 낮은 직무 재량도에서 유의한 영향을 미치는 요인으로 관찰되었다(P<0.05). 결론: 경기보조원의 근골격계 증상은 과중한 업무시간과 높은 직무요구도에 비해 낮은 직무재량도를 보이는 고긴장 직무 등에 의해 호소율이 높게 나타남을 알 수 있다. 근골격계 질환의 호소 요인에 대한 구체적인 대안의 마련과 더불어 정부기관에서 주도적으로 검토하여 경기보조원들이 속해있는 골프장 운영업체가 근골격계질환의 예방을 위한 조치와 경기보조원의 건강과 관련한 안전보건교육 등을 시행할 수 있도록 하는 방안이 마련되어야 할 것으로 본다. Objectives: This study evaluated the complaint rates of musculoskeletal symptoms and investigated the related factors of musculoskeletal symptoms in the caddies. Methods: For 316 caddies working at 6 regular golf courses, we used the self-recording questionnaires to examine general characteristics, job stress factors, subjective musculoskeletal symptoms designed by NIOSH, working environments, and working contents. Results: The complaint rates of musculoskeletal symptoms according to the musculoskeletal criteria of NIOSH were 41.8% in leg/knee/ankle/foot, 35/8% in the upper back/lower back, 28.8% in the neck, and 28.5% in the arm/wrist/fingers. Important factors affecting musculoskeletal symptoms were daily working hours during the high-demand seasons in all anatomical sites except the arm/wrist/fingers. Other related factors were degrees of winding and inclined in the golf courses, violent language and violence of customers, inability to regulate the velocity and work load control, heavy physical burden, instability of employment, and possibility of unemployment according to the specialty of caddies. As a results of multivariate logistic regression analysis, musculoskeletal symptoms of the neck, shoulders, back/lower back and leg/knee/ankle/foot were significantly influenced by working time over 12 hours in the high-demand season, and symptoms of the arm/wrist/fingers by low decision latitude (P<0.05). Conclusions: The complaint rates of musculoskeletal symptoms in the caddies were affected by working time over 12 hours and low decision latitude against excessively high psychological job demand.
Toxicoproteomic analysis of phalloidin-induced cholestasis in mouse liver
Heo, Sun-Hee,Oh, Jung-Hwa,Park, Han-Jin,Kwon, Myung-Sang,Rana, Suresh V.S,Yoon, Seok-Joo The Korean Society of Toxicogenomics and Toxicopro 2010 Molecular & cellular toxicology Vol.6 No.1
Phalloidin induces cholestasis by preventing microfilament depolymerization. Phalloidin has been widely used as an agent to induce intrahepatic cholestasis in experimental animals. The objective of this study was to examine the effects of phalloidin on protein expression profiles in mouse liver, so as to identify potential biomarkers of intrahepatic cholestasis. Phalloidin was administered to BALB/c mice at a predetermined dose of 1 mg/kg for 7 days, and phalloidin-induced cholestasis was observed. Hepatic protein expression was investigated via two-dimensional (2D) electrophoresis, and 21 protein spots showing significantly different expression between the treated and control groups were excised from the gels and identified by MALDI-TOF/TOP. The identified proteins were involved in cytoskeletal changes, lipid metabolism, gluconeogenesis, detoxification, and transport mechanisms. Among these proteins, the up-regulation of HSP90-$\beta$ in phalloidin-treated mice was confirmed by Western blot analysis and then by RT-PCR, indicating that it may serve as a useful biomarker of cholestasis. In summary, these results provide insight into the mechanism involved in phalloidin-induced cytoskeletal change and cholestasis.