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Static Induction Transistor(SIT), Drive signal phase shift control, Induction heating
노채균,김동희,김종해,남승식,정원영,심광열 嶺南大學校 工業技術硏究所 1997 工業技術硏究所論文集 Vol.25 No.1
This paper proposed a novel SIT high frequency resonant inverter having drive signal phase shift control function. Phase control type inverters using SIT can realize a power conversion at the high switching frequency with low switching loss. Especially, the high output power can be obtained by connecting the output terminal of two unit inverters in series. The stability of system using protection circuit for over current and the automatic follow-up control for load variation by using PLL are presented. This inverter produces approximately sinusoidal waveform at a high frequency, ranging from 180 Khz to 220 Khz, and is applied to the 2KW induction heating. The operating characteristics of this inverter circuit are discussed from a theoretical point of view and compared with experimental results.
고속전철 추진 시스템의 미끄럼 방지 제어기법에 관한 연구
황돈하,김동희,노채균,심광열,조규판,정원영 영남대학교 공업기술연구소 1999 工業技術硏究所論文集 Vol.27 No.2
Induction motor drive with PWM inverter control has been developed for Korean High Speed Railways. To improve traction performance, the anti-slip control(ASC) to recover adhesion must be considered. This paper describes a novel hybrid anti-slip control method for the induction motor drive. By introducing the vector control for drive system, quick response of the motor torque can be achieved when wheels are going to slip. A hybrid control scheme by mixing two conventional control methods (slip velocity feedback control and slip detection pattern control) for wheel slip and re-adhesion is proposed. This control method is simulated by motor drive, train load, and friction-creep models. The train running simulation results based on induction motor vector control with PWM inverter show that good re-adhesion characteristics are obtained.
Phase-Shift를 이용한 시분할형 부하병렬 고주파 인버터의 특성해석에 관한 연구
조규판,원재선,김동희,노채균,원규식,심광열 영남대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.28 No.2
A half bridge time sharing type load parallel high frequency resonant inverter to give VVVF function in the inverter used as power source of induction heating at high frequency is presented in this paper. This proposed inverter can reduce distribution of the switching current because of using the current of serial resonant circuit to the input current of the parallel one and this paper also realize the output control of independence irrespective of the switching frequency using Phase-Shift. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, the principle of basic operation and the its characteristics are estimated by the parameters, such as switching frequency, the variation of phase angle(φ) of Phase-Shift. It is certain that the proposed circuit will be used and expanded in the high frequency power supplies like induction heating systems.
Case Report : Necrotizing ruptured vaginal leiomyoma mimicking a malignant neoplasm
( Chae Hee Sim ),( Jin Hee Lee ),( Jyung Sik Kwak ),( Seung Hun Song ) 대한산부인과학회 2014 Obstetrics & Gynecology Science Vol.57 No.6
Leiomyomas are common benign uterine tumors. However, the incidence of vaginal myoma is very rare and may be confused with a variety of vaginal tumors. We report a case of 43-year-old nulligravida who presented with a protruding painful vaginal mass for 7 days. The mass had initially appeared 3 years prior, as 2 to 3 cm that had not subsequently increased. However suddenly, there was rapid severe enlargement over the course of 7 days. Physical exam revealed a monstrous shaped, black color with focal necrosis, odorous protruding vaginal mass about 7 cm in size. The vaginal mass was infected and degenerated. And vaginal wall was also destroyed by the enlarged mass. Because of the clinical features and radiologic findings, the preoperative diagnosis was a vaginal malignancy. We reported an extremely rare case of vaginal myoma that had several characteristics of malignancy, with a brief review of the literature.
채영란,김금순,최명애,안경애,김명애,서순림,홍해숙,정재심,박금화,이성희 대한기초간호자연과학회 2002 Journal of korean biological nursing science Vol.4 No.2
This study was aimed to analyze the variables measuring stress and imnnune responses, to identify the relationship between stress and imnnune responses, and to find out the effect of nursing interventions associated with stress and immune responses by reviewing thirty-four published articles since 1970 in Korea. The articles were selected in the field of nursing, stress management, and masters or doctoral dissertations and limited to human subject. Among these, the thirty-one articles were published since 1996 and mainly distributed in nursing(44.1%) and medicine(44.1%). The prevailing research design was nonequivalent control pre-post experimental design (41.1%). The research subjects were 55.9% for patients and 44.1% for healthy general persons including 20.6% of university students. To evaluate stress, both physiologic and psychosocial measures were adapted together in 35.3% of the articles. The most frequent two variables measuring stress and immune response were cortisol leve1(15.9%) and number or activity of natural killer ce11(25.9%). The relation between stress and immune responses was positive in 4 articles, negative in 9 cases, and none in 12 cases. Decreased stress and enhanced immune function have been found when massage, abdominal breathing, exercise, relaxation, and touch were provided as nursing interventions. The articles to investigate the relationship between stress and immune function were limited and the tested variables were diverse. Also there was no consistent evidence to correlate the stress and immune function at present. Further studies are needed to construct a valid research design and to investigate the relationship between stress and immune responses. Nursing interventions to decrease stress should be developed to result in the increased immune function and the effect of these interventions would be verified.
Chi, Hee-Jun,Park, Jun-Sang,Yoo, Chang-Seok,Kwak, Su-Jin,Son, Ho-Jeong,Kim, Seok-Gi,Sim, Chae-Hee,Lee, Kyeong-Ho,Koo, Deog-Bon The Korean Society for Reproductive Medicine 2020 Clinical and Experimental Reproductive Medicine Vol.47 No.4
Objective: This study investigated whether adding outer-well medium to inhibit osmotic changes in culture media in a dry-type incubator improved the clinical outcomes of in vitro fertilization-embryo transfer (IVF-ET) cycles. Methods: In culture dishes, the osmotic changes in media (20 µL)-covered oil with or without outer-well medium (humid or dry culture conditions, respectively) were compared after 3 days of incubation in a dry-type incubator. One-step (Origio) and G1/G2 (Vitrolife) media were used. Results: The osmotic changes in the dry culture condition (308 mOsm) were higher than in the humid culture conditions (285-290 mOsm) after 3 days of incubation. In day 3 IVF-ET cycles, although the pregnancy rate did not significantly differ between the dry (46.2%) and humid culture (51.0%) groups, the rates of abortion and ongoing pregnancy were significantly better in the humid culture group (1.5% and 49.5%, respectively) than in the dry culture group (8.3% and 37.8%, respectively, p<0.05). In day 5 IVF-ET cycles, the abortion rate was significantly lower in the humid culture group (2.2%) than in the dry culture group (25.0%, p<0.01), but no statistically significant difference was observed in the rates of clinical and ongoing pregnancy between the dry (50.0% and 25.0%, respectively) and humid culture groups (59.5% and 57.3%, respectively) because of the small number of cycles. Conclusion: Hyperosmotic changes in media occurred in a dry-type incubator by evaporation, although the medium was covered with oil. These osmotic changes were efficiently inhibited by supplementation of outer-well medium, which resulted in improved pregnancy outcomes.
이소프로판올의 탈수반응에서 지르코니아 촉매의 결정상에 따른 영향
신채호 ( Chae Ho Shin ),심혜인 ( Hye In Sim ),박정현 ( Jung Hyun Park ),조준희 ( Jun Hee Cho ),안지혜 ( Ji Hye Ahn ),최민석 ( Min Seok Choi ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.2
Zirconium hydroxide was synthesized by varying the aging time of the zirconyl chloride octahydrate at 100 oC in aqueous solution and the resulting hydroxides were calcined at 700 oC for 6 h to obtain the crystalline ZrO2. The materials used in this study were characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), N2- sorption, transmission electron microscopy (TEM), NH3 temperature-programmed desorption (NH3-TPD), CO2-TPD and iso-propanol TPD analyses to correlate with catalytic activity for the dehydration of iso-propanol. The pure tetragonal ZrO2 phase was obtained after 24 h aging of zirconium hydroxide and successive calcination at 700 oC. The increase of aging time showed the production of smaller particle size ZrO2 resulting that the higher specific surface area and total pore volume. NH3-TPD results revealed that the relative acidity of the catalysts increased along with the increase of aging time. On the other hand, the results of CO2-TPD showed the reverse trend of NH3-TPD results. The best catalytic activity for the dehydration of iso-propanol to propylene was shown over ZrO2 catalyst aged for 168 h which had the highest SBET (178 m2 g-1). The catalytic activity could be correlated with high surface area, relative acidity and easy desorption of iso-propanol.