반복치료로 호전된 호산구성 폐렴 유사 폐흡충증 1예

박세진,김희규,김봉준,이천우,옥철호,정만홍 고신대학교 의과대학 2010 고신대학교 의과대학 학술지 Vol.25 No.2

우리나라에서 인기 있는 게장등의 섭취로2) 성인뿐만 아니라 소아에서도 지속적으로 보고되고 있는 폐흡충증은 다양한 임상양상을 보일 수 있다. 저자들은 방사선 소견상 만성 호산구성 폐렴과 유사하였고, 반복적인 치료로 호전된 폐흡충증 1예를 경험하였기에 보고하는 바이다. Paragonimiasis mostly occurs by ingestion of raw or undercooked freshwater crabs or crayfish. Recently, re-emergence of paragonimiasis is reported because of ingestion of raw food such as freshwater fish and Gejang (marinated raw crabs). As the radiological features as well as the laboratory findings are similar to those of chronic eosinophilic pneumonia, the diagnosis of pulmonary paragonimiasis is often difficult and delayed. A 43 year-old female was visited our hospital for migrating and new developing consolidative lung lesions and peripheral blood eosinophilia. The eosinophil profile of leukocyte was 32% (absolute count 2,690 /mm3). Histologic finding was organizing pneumonia pattern with severe infiltration of eosinophils. Parasite specific antibody IgG forParagonimus westermani was positive (titer:0.61, normal range<0.20). After treatment with praziquantel (75mg/Kg once a day for 2days), the chest x-ray was clearly resolved. Follow-up study showed right pleural effusion, newly developed focal infiltration, and several nodules. After retreatment, we couldn't find any recurrent evidence.

低 사이클 反覆引張을 받는 構造用鋼의 疲勞强度와 疲勞크랙 傳播에 관한 硏究

吳世旭,玉致均,全泰玉,李圭用 동아대학교 공과대학 부설 한국자원개발연구소 1975 硏究報告 Vol.1 No.1

There has been many unexpected fractures of any steels used widely in many kinds of industries, which cause to a loss of lives and property. This is because the cause of fatigue demage which was not precisely considered In the conventional design. Recently it has been considered that most of fractures occurred in the design of various mechanical structures such as pressure vessels, piping, etc. are the cracks caused by low cycle fatigue. Especially it is very important in presuming the life of notched structural steel to clarify the characteristics of the low cycle fatigue crack propagation of notched structural steel. In this study, some experiments were carried out the domestic structural steel plates with "O"hole, "U" and "V" type notches under low cycle pulsating tension fatigue testing. And then the mechanism and behavior of low cycle fatigue were clarified through the consideration on the notch effect vs. fatigue strength of various notched specimens, the relations between crack propagation rate and stress intensity factor, and on the initiation of fatigue crack and its propagation, etc. The results obtained in this study are summarized as follows; (1) At the root radius R=0.25㎜ of "O" hole notch, it has higher fatigue strength and at R≥0.5㎜, almost the same in the S-N curve. But at the smaller "U" and "V" type notch root radius, it has the lower fatigue strength in the S-N curve. (2) The initiation of fatigue crack was occurred at 45~55%, 20~50% and 10~30% through each total fatigue life of the "O" hole, "U" and "V" type notch. The "O" hole notch specimen has almost the same initiation of fatigue crack without regard of notch size, but the "U" and "V" type notch specimens have the lower initiation at the larger notch root radius. (3) The "O" hole notch specimen has the lowest crack propagation rate and the incubation phenomenon of crack propagation rate occurred about 0.3㎜ of crack length. (4) Between the crack propagation rate and stress intensity factor, the value of exponent "m" was 1.11∼2.34. At the smaller root radius of "O" hole notch, the value of exponent "m" becomes the larger, but at the larger root radius of "U" and "V" type notch the value becames the smaller. (5) Propagating crack passes around or branches out on account of inclusions, with out passing through the inclusions. (6) At the smaller root radius of "U" and "V" type notch, the shape of crack propagation became more intricate, but in the case of "O" hole notch, the opposite phenomenon occurred. And at the higher stress level of each notch, the crack propagation tend to be more intricate.

알루미나이징 表面處理한 構造用鋼의 彼勞强度 및 破壞擧動에 관한 硏究

吳世旭,朴春根,全泰玉,全哲昊,周原植,李圭用 東亞大學校 大學院 1978 大學院論文集 Vol.2 No.-

Aluminizing-treated structural steel is excellent in high temperature oxidation resistance, wear resistance and corrosion resistance. So, it has been widely used for the machine parts which have required such properties. However it is difficult to find out any study result of the notched influence on the aluminizing-treated materials and the second diffusion materials. In this investigation the low carbon steel plates with with V-notches were coated with aluminum and made into second diffusion. With these specimcns the bending fatigue strength and fatigue life were observed and also crack propagation of alloy layer was investigated. The results obtained are as follows: 1) On the smoothed specimens a fatigue limit of aluminizing material was lower than the one of raw material, but it was more increased than the one of heat treatment material, and the fatigue limit of second diffusion material was lowest. 2) On the V-notched specimens a fatigue limit of aluminizing material was higher with 44% increase ratio than the one of raw material and with 63% increase ratio than the one of heat treatment material, and the rate of increase became lower increase ratio in a fatigue limit comparing to aluminzing material, with no influence of notch radius. 3) According as the notch radius became smaller, the fatigue limit became. higher on the raw material, it was same on th aluminizing material and lowest on the second diffusion material. 4) Crack initiation period was 0.04% below of fatigue crack life and the full growth period of crack propagation at alloy layer was 0.1%. The crack propagation from alloy layer to matrix was 16% of the fatigue crack life. This means that the crack propagation rate at alloy layer was very fast but the crack delay at the boundary of both was so long. 5) Crack propagation grows through defects, inclusion, peeling and previous boundary.

軸비틀린振動에 依한 Diesel Engine의 二次的 振動

吳世奎 釜山工業大學校 1969 論文集 Vol.9 No.-

This report describes the secondary vibration of a diesel engine which i formed by the torsional vibration of shafts, and the theory of the occurrence and its characteristics of the vibration which is induced by the quantity of crank pin mass. And this is described theoretically by proper calculation. The quantity of engine crank pin mass varies the revolving speed according to the torsional vibration of rotating shafts, and then produces a force to let vibration occur by which the centrifugal force and the tangential inertia force are varied. It has been found that this force causes to vibrate the rotating shafts and the engine, and that this vibration occurs at (n+1) and (n-1) degrees if the degree of the torsional vibration is n. And found by calculation, the secondary force made by the torsional vibration is not so great and it does not matter at all when the amplitude of the torsional vibration is small, but, if the engine is operated at a damper breakdown or near a point of the resonance of torsional vibration, much greater vibration will occur. So, to prevent the engine efficiency from dropping lower by such resonance of torsional vibration, some consideration should be taken. Thus, when the vibrations of engine parts are measured with a vibration gage, if any vibration of expected degree is found, the vibration at (n+1) and (n-1) degrees occurring by the torsional one should be surely examined and the instant countermeasure for the torsional vibration should be taken.

2個의 Rotor를 갖는 回轉軸系의 非線形振動

梁保錫,吳世奎 釜山水産大學校 1981 釜山水産大學 硏究報告 Vol.21 No.2

2個의 rotor가 附着된 回轉軸系에 非線形 復元力을 考慮할 경우 第一, 二共振嶺域에서 發生하는 一般的인 振動特性을 Krylov 및 Bogoljubov 法으로 解析하였고 analog 實驗으로 妥當性을 확인하였다. 定常狀態의 共振曲線 形狀은 偏心의 位相差, 非線形項의 係數 및 減衰係數에 影響을 받으며, 共振嶺域에서의 最大振幅은 特히 偏心의 位相差에 크게 影響을 받게 된다. 主共振嶺域에서 발생하는 不安定區間은 減衰의 增加에 따라 減少하여 消滅하게 된다. 理論解析과 analog 實驗의 結果가 잘 一致함을 確認하였다.

음향방출법에 의한 탄소 섬유 복합재료의 인장 및 파괴

이상국,김옥균,남기우,오세규 韓國非破壞檢査學會 1995 한국비파괴검사학회지 Vol.15 No.1

본 연구는 [0°.90°]₂s와 [0°₂/90°₂]s의 2종류 탄소섬유복합재료에 대한 인장 및 파괴인성 시험시의 파괴거동과 음향방출 특성을 해석하고 성형시의 성형압력과 인장강도 및 파괴인성 간의 상관성을 알아내기 위하여 수행되었다. AE신호는 음향방출장비를 이용하여 성형과정, 인장 및 파괴인성 시험중에 각각 검출하였다. 인장강도는 성형가압 단계수가 적을수록, 그리고 [0°/90°]₂s 시험편 쪽이 [0°₂/90°₂]s 시험편보다 높은 강도를 나타내었다. 파괴인성은 동일한 온도영역에서 거의 같은 값을 나타내나 시험온도가 높아질수록 점차 낮아짐을 알 수 있었다. 한편 인장 및 파괴인성 시험시의 파괴거동과 AE신호간의 상관성을 조사하기 위하여 AE데이터의 AE변수들에 대한 후 신호처리(post processing)와 광학현미경 및 주사형 전자현미경 관찰이 각각 수행되었다. The study was carried out to analyze the fracture behavior and the acoustic emission(AE) characteristics and to find the relationship among tensile strength, fracture toughness and cure pressure in cure process of the carbon fiber reinforced composites of two types, [0°/90°]₂s and [0°₂/90°₂]s. AE signals were detected during the curing process, tensile tests and fracture toughness tests by acoustic emission(AE) measurements, respectively. Tensile strengths showed that the less cure pressurizing steps and the side of [0°/90°]₂s specimens had the higher strengths than those of the others. Fracture toughness by change of test temperature showed nearly same values in the same temperature region, but the higher test temperature had the lower fracture toughness values. In order to examine the relationship between fracture behavior of CFRP in tensile and fracture toughness tests and AE signals, the post processing for AE parameters of AE data and the observations of microscope and SEMA have been carried out respectively.

A Study on Temperature Distribution in Inertia Welded Joints of SAE 1020 Steel Bars

Oh,Sae Kyoo 釜山工業大學校 1976 論文集 Vol.17 No.-

摩擦熱을 利用하는 熔接法에는 두가지가 있는데 즉, 非慣性摩擦熔接(摩擦熔接, Non-inertia or Conventional friction welding)과 慣性摩擦熔接(慣性熔接, Inertia friction welding or Inertia welding)이다. 摩擦熔接은 1957年 Vill1)의 指導下에 소련의 연구진2),3)에 의하여 소개되어 硏究되었고, 미국, 독일, 영국, 일본 등의 여러 나라에서도 硏究發展되고 應用되어 왔다. 이 壓接法에 의하면, 回轉動力源과 推進力下에서 固定素材와 回轉素材가 回轉, 加壓, 摩擦되어 熔接面에 熱이 發生하게 된다. 金屬이 加熱되어 所要 溫度에 달할 만큼 時間이 지나면 主軸驅動이 차단되고, 制御作用에 의해 回轉이 急停止되고 이때 推進力을 증가시켜 熔接이 完成된다. 이때 熔接面에 作用하는 Energy入力은 약 1.6 ps/㎠에 제한되며, 熔接時間은 10∼30초에 달하고(最近의 報告에서는 7초 정도4),5),6)), 이 긴 時間은 粒子成長을 촉진시키는 결과가 되며, 熔接變數가 回轉數, 加熱時間, 加壓壓力, 加壓時間의 5가지나 되어 같은 熔接 cycle에 對해서도 일관성 있는 熔接結果를 반드시 얻지는 못하며 (upset量의 散布 및 壓接備向이 보다 큰 편임6)), 어느 특수 材質에 대해서는 壓接이 곤란하거나 불가능한 경우가 있다. 慣性熔接은 미국에서 開發硏究되어7),8) 1966年 9月 20日에 Oberle, Caltom, Loyd, White에 의하여 Caterpillar Tractor Co.에 양도된 美 特許 3272233에 근거를 두고 發展應用되었다.9) 이 壓接法은 첫째, flywheel과 chuck 및 한쪽 素材가 一定速度로 加速回轉되고, 둘째로 回轉軸에 動力이 차단되면 이 回轉素材가 固定素材에 의해 加壓되고, 慣性에 의해 계속 回轉하는 flywheel의 回轉速度가 감속됨에 따라 flywheel에 저축되었던 運動 energy(慣性 moment)가 全部 摩擦熱로 전환되어 두 熔接物의 熔接面이 plastic溫度下에서 回轉과 加壓에 依한 forging work를 일으켜 불순물이나 voids를 제거시키고, 粒子組織을 refine시키게 되며, 세째로, 回轉이 정지 됨에 따라 高强度의 熔接이 完成되는 것이다. 慣性熔接은 熔接性能이 우수하고, 作業이 간단하며, 經濟的이고 多量生産이 可能하며, 熔接變數는 回轉速度, flywheel部의 慣性 moment 및 推力(加壓力)의 세가지 뿐이며, 熔接時間이 1∼5초에 불과하며, 熔接單位面積當 入力比가 3.1∼23.6 ps/㎠이고, 非熔接狀態에서 plastic forging이 이루어져 좁은 熱影響部에서의 粒子組織이 치밀하고, flux 등의 용접첨가물이 全혀 不必要하고, 特殊재질 및 異種재질의 捧과 捧, 捧과 板, 捧과 管, 管과 管, 管과 板 等의 熔接보다 우수하다는 장점이 있다10),11),12). 이러한 우수한 壓接法인 慣性熔接에 依한 熔接部의 性能에 절대적 영향을 미치는 熔接摩擦熱的 擧動에 對한 硏究報告가 매우 적다. 그리고 國內에서는 全無하다. 따라서, 本 硏究는, 入力 決定 및 熱傳導方程式에 關한 理論과 慣性熔接에서의 순간적 溫度分布를 SAE 1020熔接棒에 對해서 實驗的으로 조사하였다. 접촉면에서의 熱入力決定은 實驗 data에서 얻은 回轉速度 및 全熔接時間에 근거를 두었다. 지름 Φ9.5㎜의 試片(SAE 1020 間壓延軟鋼棒)의 熔接面에서 固定側 試片의 0.8mm와 2.4mm인 곳에, 中心部, 半徑中央部 및 外周部 등 全 6個所에 對를 軸에 45° 方向으로 삽입 熔接하여, electro-optical recorder에 依하여 熔接時間에 對한 熔接部 溫度曲線을 얻었다. (實驗은 著者의 湍美中 Production Technology Inc.에서 行해졌음). 硏究結果는 다음과 같다. 1) 熔接面에 對한 熱入力決定은 다음 式으로 表示된다. q(r, t)=44.1 A·r·n(t) 2) 熔接部 溫度分布는, 熔接 cycle의 後期에서는, Caterpillar의 實驗結果와 거의 一致했으며, 熔接初期에서의 差異点은 實驗裝置 改善 및 油壓裝置를 利用한 熔接機信賴度 改善에 依해 현저히 減少될 수 있다. 3) 同一 크기의 低炭素鋼棒 壓接에 있어서, 從來의 摩擦熔接의 境遇는, 熔接面 外周部에서 最高溫度 1299℃에 달하는데 20초 걸렸으며, 溫度 勾配도 緩慢한데 比하여, 慣性熔接의 境遇는 熔接面의 0.8mm인 곳이 外周部에서 약 1300℃에 달하는데 不過 0.4초 도는 그 以前이였고, 溫度句配도 훨씬 더 急激하였다. 이때 熔接面 全域의 溫度가 熔接材의 鍛造溫度 範圍보다 약간 높으나, 熔接面에서 塑性變形된 재료가 均一壓力에 依하여 熔接界面으로부터 壓出되어 flash를 形成하게 된다. 4) 慣性熔接의 境遇, 熔接面의 最高溫度 範圍가 同一재료에 對해서 從來 摩擦熔接의 境遇와 對等하다. 그러나 熔接面 온도는 어느 경우이든 upsetting(加壓)을 고려하는 限, 재료의 劇点에 達할 수 없다.

SM45C와 SCM4의 마찰용접 및 피로특성에 관한 연구

오세규(Sae-Kyoo Oh),김부안(Bu-Ahn Kim),김선진(Seon-Jin Kim),남상훈(Sang-Hoon Nam) 한국해양공학회 1988 韓國海洋工學會誌 Vol.2 No.2

A study on friction welding of carbon steel bar (SM45C) to chrome molybedenum steel bar(SCM4) is examined experimentally through tensile test, hardness test, microstructure test and fatigue test.<br/> So, this paper deals with optimizing the welding conditions and analyzing various mechanical properties about friction welds of SM45C to SCM4 steel bars.<br/> The results obtained are summarized as follows;<br/> 1) For friction welded joints of SM45C to SCM4 steel bars, the total upset(U)increases linearly with an increase of heating time(t₁) till 6 s.<br/> 2) The determined optimum welding conditions are heating time (t₁),2s, upsetting time(t₂),3 s, heating pressure (P₁), 4㎏f/㎟(39.2MPa), upsetting pressure(P₂), 8㎏f/㎟(78.4MPa) and rotating speed(N), 2,000rpm when the total upset(U) is 3.4㎜, resulting in a computed relationship between the joint tensile strength ot(㎏f/㎟) and the total upset U(㎜);<br/> ot=0.21U³-3.38U²+ 17.03U +66.00<br/> 3) As the elongation is increased more and more, the fracture position becomes away from weld interface and the fractures are similar to those of SM45C. Fracture is taken place on SM45C side.<br/> 4) The weld interface of two dissimilar materials is mixed strongly, and the heat affected zone is about 2.0㎜ at SM45C while about 2.7㎜ at SCM4 side. Therefore, the welded zone and heat affected zone are very narrow, comparing with those of the joints welded by the other welding methods.<br/> 5) The fatigue strengths at N = 10<SUP>6</SUP> cycles of SM45C, SCM4 and friction welded joints are 23㎏f/㎟(225.4MPa), 33㎏f/㎟(220.5MPa), and 22.5㎏f/㎟(220.5MPa) respectively, and fracture at friction welded joint takes place at the side of SM45C.<br/> 6) The hardness of the friction weld interface is 3 times higher than that of base metal.<br/> 7) Fatigue strength of friction welded joint is higher than that of base metal.<br/> 8) Notch sensitivity factor of friction welded joint is lower than that of base metal.

慣性熔接된 異種材質 IN713C-SAE8630의 熔接性能에 回轉速度가 미치는 影響

吳世奎(Sae Kyoo Oh) 대한조선학회 1972 大韓造船學會誌 Vol.9 No.2

토션바材의 摩擦熔接에 관한 硏究(Ⅱ)

吳世奎(Sae-Kyoo Oh),李鍾斗(Jong-Doo Lee) 한국해양공학회 1990 韓國海洋工學會誌 Vol.4 No.2

This paper deals with investigating experimentally the effects of PWHT on the weld quality such as strength, toughness, hardness and micro-structure of the welded joints in friction welding of torsion bar material SUP9A bar to bar.<br/> The results obtained are summarized as follows ;<br/> 1) It was certified that the condition of the post-weld heat treatment(PWHT) for the friction welded joints was very satisfactory because both strength and toughness of the joints were improved as almost same as those of the base metal or better by the PWHT.<br/> 2) The peak of hardness distribution of the friction welded joints can be eliminated by PWHT, resulting in being almost equalized at the weld interface, the HAZ(heat affected zone) and the base metal.<br/> 3) The micro-structure of the base metal, HAZ and weld interface(WI) of friction welded joints welded at the optimum welding condition consists of the same sorbite structure obtained by PWHT and fined sorbite at WI, resulting in increasing toughness as well as strength, and no micro structural defect has been found at the friction welded zone.