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[論文] 鋼材의 衝擊疲勞破壞壽命에 미치는 Tempering 效果에 관한 硏究
정재천(Chae-Cheon Cheong) 한국자동차공학회 1981 오토저널 Vol.3 No.3
The fatigue characteristics of Si-Mn spring steel (AISI'9260-H, JIS SUP-6) were investigated on several heat treatment conditions, Repeated impact loads of 10kg-cm and 15kg-cm energy were applied with a cam roller drop hammer type impact fatigue testing machine.<br/> Specimens were oil-quenched, and tempered at 350℃, 400℃, 450℃ and 500℃, respectively. Results obtained in these experiments are summerized as follows. :<br/> 1) The fatigue life of the specimen is decreased as the magnitude of constant impact energy is increased, regardless of heat treatment.<br/> 2) Generally, the fatigue life of the specimn is decreased as the tensile strength of the materials is increased.<br/> 3) Within the limit of these experiments, the fatigue life showed abrupt decrease at the tempering temperature of about 400℃.<br/> 4) The fatigue life is increased as the initial value of applied stress intensity factor (K₁) is decreased. This tendency is apparent for the low tensile strength materials.
정재천(Jung, Jea-Chun),이창남(Lee, Chang-Nam),이승환(Lee, Seung-Hwan),김형섭(Kim, Hyoung-Seop) 대한건축학회 2014 大韓建築學會論文集 : 構造系 Vol.30 No.11
The Centrifugal Reinforced Concrete(CRC) column developed by SEN Engineering is a method utilizing PHC(Prestressed High Strength Pre-Stressed Concrete) piles as columns. The CRC column is able to obtain the maximum capacity as for a reinforced concrete column due to its manufacturing method using centrifugal force to produce high strength concrete same for PHC and inserting a reinforced cage instead of a pre-stressed wire decreasing compressive strength in PHC. This expeditious and economical way to produce concrete of strength more than 80MPa by centrifugal casting makes CRC columns be easily and quickly applied to the construction site than PC(Precast Concrete). CRC column is not only improve applicability but it also enhances constructability because its buckling capacity higher than H-section column leads to increase the depth of penetration. If a required service load is higher than the capacity of the CRC column, it can be reinforced by additional concrete casting with re-bars in the site to obtain sufficient strength. The seismic resistance performance of the CRC column-to-TSC beam connection is previously demonstrated in accordance with KBC 2009 by experimental test, and the real scale test of the connection is conducted in this study. As a result, the seismic resistance performance of the connection meets the requirements of KBC2009; therefore, the CRC column-to-TSC beam connection can be used as IMF or SMF.
수소 Plasma 처리 후의 MgO 보호막에 대한 일함수 변화 측정
정재천,이석주,조재원,Jeong, Jae-Cheon,Rhee, Seuk-Joo,Cho, Jae-Won 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.7
The changes in the work $function({\Phi}_w)$ in the MgO protective layers after $plasma(Ar,\;H_2)$ treatment have been studied using ${\Upsilon}-focused$ ion beam $({\Upsilon}-FIB)$ system. The ${\Phi}_w$ was determined as follows: Ar-plasma $treatment({\Phi}_w=4.52eV)$, $H_2-plasma$ $treatment({\Phi}_w=5.65eV)$, and non-plasma $treatment({\Phi}_w=4.64eV)$. The results indicated that the H-plasma could not make any effective physical etching due to the small masses of hydrogen atoms and molecules while the hydration of H-plasma could grow some contaminating materials on the surface of MgO.
경골 결절부의 통풍성 결절 및 동반된 경골 상부 국한성 연조직염
정재천 ( Jae Cheon Jeong ),박창하 ( Chang Ha Park ),조한균 ( Han Kyun Cho ),최성식 ( Sung Sik Choi ),서명덕 ( Myung Deok Seo ),임용성 ( Yong Seong Lim ),송영욱 ( Yeong Wook Song ) 대한류마티스학회 2004 대한류마티스학회지 Vol.11 No.2
Gout is characterized by hyperuricemia and recurrent attacks of acute arthritis. Gout is a clinical syndrome resulting from the deposition of urate (monosodium urate monohydrate) crystals. Urate deposition occurs in articular cartilage, subchondral bone, synovial membrane, joint capsule and periarticular tissues, with articular cartilage being especially susceptible. The first metatarsophalangeal joint is commonly involved at presentation and other commonly affected joints are the ankle, knee and tarsal area. Gouty tophus located on the tibial tuberosity has never been reported in korea. We report a case of gouty tophus on the tibial tuberosity with (chemical) cellulitis occurred at the upper tibial area in a 46-year-old man.