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Lyu, Sung-Ki,Lu, Long,Wei, Yun-Long Korean Society for Precision Engineering 2006 International Journal of Precision Engineering and Vol.7 No.2
We propose a new concept of transmission-tribology design based on the investigation of development and existing problems of the gear drive and tribology. The content of transmission-tribology and transmission-tribology design is probed. Some effective methods of transmission-tribology design is probed. Some effective methods of transmission-tribology design are put forward. Partial achievements in this research are introduced tersely. Mechanical transmission, which is represented by the gear drive, and tribology are two main branches of mechanical engineering. They have their own definite research field. In recent years, we have been doing our utmost to suggest combining mechanical transmission-tribology and transmission-tribology design. Partial achievements in this research area are obtained.
Lyu, Sung-Ki,He, Hui-Bo,Lu, Long,Youn, Il-Joong Korean Society for Precision Engineering 2006 International Journal of Precision Engineering and Vol.7 No.4
SCM415 alloy was implanted with nitrogen ions using plasma source ion implantation (PSII), at a dose range of $1{\times}10^{17}\;to\;6{\times}10^{17}\;N^+cm^{-2}$ Auger electron spectrometry (AES) was used to investigate the depth profile of the implanted layer. Friction and wear tests were carried out on a block-on-ring wear tester. Scanning electron microscopy (SEM) was used to observe the micro-morphology of the worn surface. The results revealed that after being implanted with nitrogen ions, the frictional coefficient of the surface layer decreased, and the wear resistance increased with the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker oxidative wear with the increase in the nitrogen dose. The effects were mainly attributed to the formation of a hard nitride precipitate and a supersaturated solid solution of nitrogen in the surface layer.
Sung-Ki Lyu,Long Lu,Yun-Long Wei 한국정밀공학회 2006 International Journal of Precision Engineering and Vol.7 No.2
We propose a new concept of transmission-tribology design based on the investigation of development and existing problems of the gear drive and tribology. The content of transmission-tribology and transmission-tribology design is probed. Some effective methods of transmission-tribology design is probed. Some effective methods of transmission-tribology design are putforward. Partial achievements in this research are introduced tersely. Mechanical transmission, which is represented by the gear drive, and tribology are two main branches of mechanical engineering. They have their own definite research field. In recent years, we have been doing our utmost to suggest combining mechanical transmission-tribology and transmission-tribology design. Partial achievements in this research area are obtained.
Lyu, Sang Woo,Kim, Ji Won,Choi, Chang Hwan,Seok, Hyun Ha,Yoon, Tae Ki,Kim, Ari Informa UK, Ltd. 2013 Gynecological endocrinology Vol.29 No.5
<P>Basal luteinizing hormone (LH) levels have also been suggested to impact on ovarian responsiveness as well as basal follicular stimulating hormone (FSH) levels. The aim of this study was to compare the <I>in vitro</I> fertilization (IVF) outcomes according to cycle day 3 FSH/LH ratio and to assess the proper stimulation protocol between gonadotropin-releasing hormone (GnRH) agonist and GnRH antagonist protocols. The retrospective cohort study recruited a total of 1211 women having the laboratory values of FSH (<10 IU/L) and LH within 3 months before IVF. Patients were treated with GnRH agonist long or GnRH antagonist protocols and stimulated with recombinant FSH (rFSH). The number of total retrieved oocytes and mature oocytes, implantation rate, clinical pregnancy rate and ongoing pregnancy rate were analyzed between groups: Group I: FSH/LH < 2 and Group II: FSH/LH ≥ 2. The Group II had the small number of retrieved oocytes and mature oocytes compared to the Group I (<I>p</I> = 0.000). Clinical and ongoing pregnancy rate were lower in Group II (<I>p</I> = 0.006, 0.006, respectively). In comparison of each protocol within groups, Group II showed significantly low pregnancy rate when GnRH antagonist was administered. In women with normal FSH level, high day 3 FSH/LH ratio can present subclinically low ovarian reserve and be predictive of lower pregnancy outcomes in fresh IVF cycles, and the choice of GnRH agonist can be related to favorable IVF outcomes.</P>
Characteristic of Quenching Refrigerant for Heat Treatment Deformation Control of SM45C Steel
Lyu, Sung-Ki The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.5
This study deals with the characteristic of quenching refrigerant for heat treatment deformation control of SM45C steel. Heat-treatment deformation must be controlled for the progress of production parts for landing gear. Most of deformation is occurred on inconsistent cooling. The inconsistent cooling is caused by a property of quenching refrigerant. When a heated metal is deposited in the quenching refrigerant, the cooling speed is so slow in early period of cooling because of a steam-curtain. After additional cooling, the steam-curtain is destroyed. In this progress, the cooling speed is very fast. The object of this study is to control the deformation of heat-treatment for landing gear by improving the conditions of quenching. The cooling curves and cooling rates of water, oil and polymer solution are obtained and illustrated. From the characteristics of the quenching refrigerant, the effects of heat-treatments on thermal deformation and fatigue strength are also investigated.
Laser therapy in patients with suprastomal tracheal stenosis after tracheostomy
( Ki Hyun Seo ),( Cheol Kim ),( Ji Hyun Oh ),( Ji Won Lyu ),( Ho Sung Lee ),( Jae Sung Choi ),( Ju Ock Na ),( Yong Hoon Kim ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-
Background: Tracheal stenosis after some of the classical non-flap surgical tracheostomy was observed cranial to the tracheostoma and consisted of scar and granulation tissue. Operation is associated with significant morbidity and a low mortality rate, although tracheal resection and end-to-end anastomosis has been recommended to treat this condition. Alternatively, laser surgery could allow the immediate coagulation and resection of tracheal stenosis without recurrence. The purpose of this study is to evaluate the safety and effectiveness of diode laser therapy in patients with suprastomal tracheal stenosis after tracheostomy accompanied with severe cough, dyspnea. Methods: A prospective analysis of patients who underwent laser therapy during the 5-yearh period was performed. We investigated the result of treatment before and after procedure as well as the recurrence of stenosis. Results: Eighteen patients underwent the first laser session and one patient received the second session 2.4 years after laser therapy by a otolaryngologist. The mean age of the patients was 54.5 ± 17.4 years (13 males, 6 females; age range: 9 - 77 years). All of patients except one patient performed the removal of granuloma with a large forcep after one session of laser treatment without complication. Six months after the laser ablation, 16 of 17 patients had much improvement of symptoms with a complete recanalization. In addition, 13 of 14 patients who attempted decannulation were successful. Conclusion: The laser resection in patients with suprastomal tracheal stenosis after tracheostomy was a highly effective, safe, long-standing therapeutic method with its immediate visible effect.
Sung-Ki Lyu,Hui-Bo He,Long-Lu,Iljoong Youn 한국정밀공학회 2006 International Journal of Precision Engineering and Vol.7 No.4
SCM4I5 alloy was implanted with nitrogen ions using plasma source ion implantation (PSII), at a dose range of 1×10¹? to 6×10¹? N? ㎝-². Auger electron spectrometry (AES) was used to investigate the depth profile of the implanted layer. Friction and wear tests were carried out on a block-an-ring wear tester. Scanning electron microscopy (SEM) was used to observe the micro-morphology of the worn surface. The results revealed that after being implanted with nitrogen ions, the frictional coefficient of the surface layer decreased, and the wear resistance increased with the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker oxidative wear with the increase in the nitrogen dose. The effects were mainly attributed to the formation of a hard nitride precipitate and a supersaturated solid solution of nitrogen in the surface layer.
Characteristic of Quenching Refrigerant for Heat Treatment Deformation Control of SM45C Steel
Sung-Ki Lyu 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.5
This study deals with the characteristic of quenching refrigerant for heat treatment deformation control of SM45C steel. Heat-treatment deformation must be controlled for the progress of production parts for landing gear. Most of deformation is occurred on inconsistent cooling. The inconsistent cooling is caused by a property of quenching refrigerant. When a heated metal is deposited in the quenching refrigerant, the cooling speed is so slow in early period of cooling because of a steam-curtain. After additional cooling, the steam-curtain is destroyed. In this progress, the cooling speed is very fast. The object of this study is to control the deformation of heat-treatment for landing gear by improving the conditions of quenching. The cooling curves and cooling rates of water, oil and polymer solution are obtained and illustrated. From the characteristics of the quenching refrigerant, the effects of heat-treatments on thermal deformation and fatigue strength are also investigated.