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김기열(Ki-Youl Kim),김상호(Sang-Ho Kim),이범주(Beom-Joo Lee),조정환(Jeong-whan Cho) 한국철도학회 2002 한국철도학회 학술발표대회논문집 Vol.- No.-
The Friction Brake Pad of High Speed Train is the most important parts in brake system, which is usually made of Cu-based Sintered friction material. This study has been carried out about the formulation effects of sintered friction material and made lots of sample brake pads. Then, we have done the performance test of the developed product by using full scale inertia Dynamo-meter. This performance test (braking speed 300㎞/h) was conducted as GEC Alsthom Standard test procedure and High Speed Brake Test (braking speed 350㎞/h) was done at "Poli" in Italy. The friction properties of this product was almost identical with the brake pad which is currently used to TGV. And the temperature of brake disk on braking speed 350Km/h was a little higher.
박경식(Park Kyung-sik),강성웅(Kang Sung-woong),조정환(Cho Jeong-whan),이희성(Lee Hisung) 한국철도학회 2005 한국철도학회 학술발표대회논문집 Vol.- No.-
Brake system is indispensible functional part to the transportation machines such as railroad cars, and all of industrial machines. It is mechanical element to stop the movement or slow the speed, transforming kinetic energy of motion object into thermal energy through solid friction. According that recently the railroad cars have become high-speed, the technique in braking domain to secure the overall braking effort is making rapid progress. In particular, material development and manufacturing process are so important to secure friction performance, which is the core in braking performance of mechanical brake units. Wear of brake disk could mainly result in the diminishment of its life span due to thermal cracking, so the endurance against high temperature is required. On the other hand, in this case, the problem is that the side wear of pad, relative material is slightly increased because of enlargement of plastic deformation. It is necessary, therefore, to develop a disk material that will be used in the Tilting System mechanical brake units. The purpose of this paper is to make a study prior to developing brake disk of Tilting Train travelling at 200㎞/h and to propose the component of brake disk. Accordingly, I will conduct sufficient researches on technical documents of brake disk, that are basic documentations, analyze an impact on components, and further, considering braking degree of train, study for the basic proposal on brake disk"s component of the train travelling at 200㎞/h, which has relatively minor influence of heat stress and maintains the friction. In this respect, I would like to investigate friction characteristics between disk and relative friction material via Test on some possible test segments, analyze and propose friction performance, temperature impact and so forth coming from the contact with pad, relative material to demonstrate the friction characteristics.
요골접근법에 의한 관상동맥 스텐트 시술의 가능성과 안정성
차광수(Kwang Soo Cha),김무현(Moo Hyun Kim),김혜진(Hye Jin Kim),양두경(Doo Kyung Yang),조정환(Jeong Whan Cho),박태호(Tae Ho Park),박형렬(Hyung Ryul Park),김봉근(Bong Keun Kim),김영대(Young Dae Kim),김종성(Jong Seong Kim) 대한내과학회 1999 대한내과학회지 Vol.56 No.2
Objectives : Powerful anticoagulant and antiplatelet therapies after coronary stenting may carry the risk of increased bleeding complications if large-bore guiding catheters are introduced via the femoral artery. Recently smaller radial artery is introduced as an entry site for coronary interventions owing to miniaturization of equipments, easy hemostasis and lower access site complications, and little hand ischemia. The purpose of this study is to evaluate the feasibility and safety of coronary stent implantation via the radial artery. Methods : After a learning curve for transradial diagnostic coronary angiography, stent implantation was attempted in 131 consecutive patients, 135 lesions. Immediately after procedure, the introducer sheath was withdrawn and mobilization was initiated. Clinical follow-up was done for punctured radial arteries. Results : Procedural success and uncomplicated clinical course was achieved in 129(98%) patients, 133(99%) lesions. No stent embolization or migration within the coronary artery, and no procedure-related death, Q wave myocardial infarction or emergent bypass surgery were happened. No stroke or severe arm vessel complications were happened except 4(3%) cases of moderate hematoma. Failed 2 cases were in early period and stents did not pass the lesions due to inappropriate selection and poor backup of guiding catheters. During follow-up of 124±36 days, punctured radial arteries showed weak or absent radial pulse in 10(7%) patients, but no claudication or ischemia of hand was observed. Conclusion : Transradial coronary stenting was performed safely with high success rate and low complication rate. This study supports that transradial approach is a promising primary route for coronary stenting.