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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,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.
Development of a Type 4 Composite Cylinder for Self-contained Breathing Apparatus
Sung-min Cho(조성민),Da-eun Kim(김다은),Hye-jin Seong(성혜진),Young-kyu Ko(고영규),Hong-chul Kim(김홍철),Kang-ok Lee(이강옥),Min-sik Jo(조민식),Sung-ki Lyu(류성기) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.12
Aluminum liners used in cylinders are hazardous for human health. In this study, we use a plastic PA liner inside cylinders to solve this problem. Plastic PA liners are widely used in the manufacturing industry in the production of food and beverage containers. We covered the aluminum boss with a plastic liner material and wound the composite fibers over the liner material. To reinforce the dome area, we used low strength / high elongation plastic liner. To predict the performance of the developed product, we conducted structural analyses utilizing the 3D laminated solid element. We verified the soundness of the product by testing the prototype.
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.
Development of Subminiature Type 3 Composite Pressure Vessel for Cooling Unit in Electric Appliances
Sung-Min Cho(조성민),Seung-kuk Lee(이승국),Jong-sam Moon(문종삼),Sung-ki Lyu(류성기) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.6
In this study, we have developed a composite pressure vessel that is compact and can store refrigerant at high pressure to increase the refrigerant volume. The composite pressure vessel is made of aluminum-based duralumin, which has high rigidity and excellent elongation in the inner liner, considering the characteristics of products in the aerospace and defense industry, where the safety of the applied product is considered as a priority. High strength carbon fiber was applied to the outside. In order to evaluate the performance of the developed product, burst test and cycling test were carried out. In burst test, an excellent safety margin equivalent to 2.7 times the operating pressure was obtained. In cycling test, a stable failure mode in which "pre-burst leak" occurs is proved and the soundness of the product is proved.
A Study on Monitoring Drilling using Torque from Main Spindle Based on PLC in CNC Machine Tools
Sang-hwan Yoon(윤상환),Sung-min Moon(문성민),Sung-ki Lyu(류성기) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.3
Drilling processes require a cutting monitoring function that can be analyzed and gives feedback about strange conditions, tool collision and tool wear in real time. In this study, we proposed a drill monitor using the torque from the main spindle in CNC machine tools and a PROFIBUS network as a PLC-based interface. This paper studied drilling torque changes depending on drill size, the repetition cutting of the drilling and the drill"s wear in the same cutting conditions. The material of the drills was high speed steel (HSS) and uncoated. The drills chosen were 2.7 mm, 6.7 mm, and 10.0 mm in diameter. These drills were selected because they had basic holes for their taps.
Sung-Min Cho(조성민),Seung-kuk Lee(이승국),Min-sik Cho(조민식),Sung-ki Lyu(류성기) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.6
In this study, we solved the human hazard problem of aluminum liner by applying plastic PET liner which is widely used as a material for food and beverage containers in the market. In order to reinforce dome area by using low strength / high elongation plastic liner, The aluminum boss was covered on the plastic liner surface. In order to predict the performance of the developed product, the structural analysis was carried out by applying the three - dimensional laminated solid element, and the soundness of the product was verified through the prototype performance test.
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.
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.