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Space holder 방법으로 제조된 다공질 타이타늄의 기계적 성질에 대한 Computed-Tomography를 이용한 유한요소해석
이동준,안동현,이병갑,정지원,오상호,이종수,김형섭,Lee, Dong Jun,Ahn, Dong-Hyun,Lee, Byounggab,Jeong, Jiwon,Oh, Sang Ho,Lee, Chong Soo,Kim, Hyoung Seop 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.5
In this study, porous titanium samples were manufactured by space holder methods using two kinds of urea and sodium chloride space holders. Three-dimensional pore structures were obtained by a computed-tomography (CT) technique and utilized for finite element analysis in order to investigate the mechanical properties. The CT-based finite element analyses were in better agreement with the experimental results than unit cell model-based analyses. Both the experimental and CT-based results showed the same tendency that the elastic modulus decreased with increasing the porosities. The total porosity of the bulk body plays a key role in determining the elastic modulus of porous materials.
최준길 ( Jun Kil Choi ),오사무미타무라 ( Osamu Mitamura ),이동준 ( Dong Jun Lee ),신현선 ( Hyun Seon Shin ) 한국환경생태학회 2008 한국환경생태학회지 Vol.22 No.6
2006년 5월부터 2007년 5월까지 동강의 어류상과 생태학적 군집분석을 조사한 결과는 다음과 같다. 조사된 어종은 총 10과 31종이었다. 총 31종의 어종 중 일차담수어가 26종, 주연성 담수어가 5종으로 나타나 일차담수어의 구성비가 매우 높았다. 우점종은 참갈겨니(Zacco koreanus) 55.73%, 아우점종은 쉬리(Coreoleuciscus splendidus) 7.15%였으며, 우세종은 배가시리(Microphysogobio longidorsalis) 6.12%, 어름치(Hemibarbus mylodon) 4.87%, 참종개(Iksookimia koreensis) 4.49% 등이었다. 한국고유종은 묵납자루(Acheilognathus signifer), 줄납자루(A. yamatsutae), 가는돌고기(Pseudopungtungia tenuicorpus), 쉬리(C. splendidus), 긴몰개(Squalidus gracilis majimae) 그리고 어름치(H. mylodon) 등 19종(61.29%)으로 고유종의 빈도가 매우 높았으며, 천연기념물이 1종, 환경부지정 멸종위기 야생동물 II급 종이 5종으로 각각 확인되었다. 예상되는 종수(기대종)의 분석 결과, 동강의 전 조사지점에서는 18(지점 4, 5)∼22종(지점 3)이 서식하고 있을 것으로 나타났으며, 유사도 분석은 62.28%(지점 1과 2)∼84.13%(지점 1과 5)의 범위로 나타났다. 따라서 동강유역은 어류가 서식하기에 매우 적합한 수환경을 유지하고 있으며, 각 조사지점별 수환경도 매우 유사한 것으로 판단된다. The ichthyofauna and ecological community analysis in the Dong River, Korea, were investigated from May, 2006 to May, 2007. During the surveyed period, 31 species belonging 9 families were collected. Total of 31 species(primary freshwater: 26 species, peripheral freshwater: 5 species) were found with the primary freshwater fishes being highest. Dominant species was Zacco koreanus(55.73%), and subdominant species was Coreoleuciscus splendidus(7.15%). Also, Microphysogobio longidorsalis (6.12%), Hemibarbus mylodon(4.87%), Iksookimia koreensis(4.49%) were numerous. There were 19 Korean endemic species(61.29%), including Acheilognathus signifer, A. yamatsutae, Pseudopungtungia tenuicorpus, C. splendidus, Squalidus gracilis majimae, H. mylodon. Among them, 1 species was identified as qualifying for possible desigantion as a natural monument catergory, and 5 species were identified for designation required to protect under a wildlife category. As result of expected number of species according to rarefaction curve, the expected species of the Dong-river ranged from 19(St. 4, 5) to 22(St. 3) and result of similarity analysis ranged from 62.28%(St. 1 and 2) to 84.13%(St. 1 and 5). In conclusions, we could define that the Dong-river has a very good water conditions as habitat of fish, and habitat conditions also are very similar in every survey sites.
이동준,김찬용,Lee, Dong-Jun,Chung, Chan-Yong 대한흉부심장혈관외과학회 1978 Journal of Chest Surgery (J Chest Surg) Vol.11 No.3
Sixty-one bronchiectatic patients were reviewed who were treated by surgical intervention in the Department of Thoracic and Cardiovascular Surgery, Chonnam University Hospital during the recent 14 years from January of 1965 to August of 1978. 1. Various pulmonary resection was performed; lobectomy was 55.5%, lobectomy and segmental resection 20.6%, bilobectomy 13.1%, lobectomy, segmental resection and thoracoplasty 4.9% and pneumonectomy was 3. 2%. 2. The most common associated disease was pulmonary Tbc, its frequency was 47.5% and next was chronic bronchitis [31%]. 3. The postoperative complication was observed in 19.6% [12 cases] and the most common was wound infection. 4. The possibility of recurrence was relatively high in the cases of residual lesion and it needs more intensive medical care. 5. The surgical result was satisfactory in 86.9% (53 cases), slight improvement in 4.9% (3 cases) and the mortality rate was 1.6% (1 case).
이동준,윤은유,강수영,이정환,김형섭,Lee, Dong-Jun,Yoon, Eun-Yoo,Kang, Soo-Young,Lee, Jung-Hwan,Kim, Hyoung-Seop 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.5
In this study, electrolytic copper powders were consolidated by high-pressure torsion process (HPT) which is the most effective process to produce bulk ultrafine grained and nanocrystalline metallic materials among various severe plastic deformation processes. The bulk samples were manufactured by the HPT process at 2.5 GPa and 1/2, 1 and 10 turns. After 10 turns, full densification was achieved by high pressure with shear deformation and ultrafine grained structure (average grain size of 677 nm) was observed by electron backscatter diffraction and a scanning transmission electron microscope.
유한요소해석을 이용한 고압비틀림 공정 중의 구리 분말의 치밀화 및 고형화 거동 분석
이동준,윤은유,Lee, Dong Jun,Yoon, Eun Yoo 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.1
In this study, the behavior of densification of copper powders during high-pressure torsion (HPT) at room temperature is investigated using the finite element method. The simulation results show that the center of the workpiece is the first to reach the true density of copper during the compressive stage because the pressure is higher at the center than the periphery. Subsequently, whole workpiece reaches true density after compression due to the high pressure. In addition, the effective strain is increased along the radius during torsional stage. After one rotation, the periphery shows that the effective strain is increased up to 25, which is extensive deformation. These high pressure and severe strain do not only play a key role in consolidation of copper powders but also make the matrix harder by grain refinement.
수분사법으로 제조된 순철분말의 성형성에 미치는 분말크기의 영향
이동준,윤은유,김하늘,강희수,이언식,김형섭,Lee, Dong-Jun,Yoon, Eun-Yoo,Kim, Ha-Neul,Kang, Hee-Soo,Lee, Eon-Sik,Kim, Hyoung-Seop 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.3
In the current study, the effects of particle size on compaction behavior of water-atomized pure iron powders are investigated. The iron powders are assorted into three groups depending on the particle size; 20-45 ${\mu}M$, 75-106 ${\mu}M$, and 150-180 ${\mu}M$ for the compaction experiments. The powder compaction procedures are processed with pressure of 200, 400, 600, and 800 MPa in a cylindrical die. After the compaction stage, the group having 150-180 ${\mu}M$ of particle size distribution shows the best densification behavior and reaches the highest green density. The reason for these results can be explained by the largest average grain size in the largest particle group, due to the low plastic deformation resistance in large grain sized materials.
분말 표면 조도의 3차원 레이저 분석기를 이용한 정량화와 압분성형체 강도에 미치는 영향 분석
이동준,윤은유,김하늘,강희수,이언식,김형섭,Lee, Dong-Jun,Yoon, Eun-Yoo,Kim, Ha-Neul,Kang, Hee-Soo,Lee, Eon-Sik,Kim, Hyoung-Seop 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.5
Green strength is an important property of powders since high green strength guarantees easy and safe handling before sintering. The green strength of a powder compact is related to mainly mechanical and surface characters, governed by interlocking of the particles. In this study, the effect of powder surface roughness on the green strength of iron powders was investigated using a transverse rupture test. Three-dimensional laser profiler was employed for quantitative analyses of the surface roughness. Two different surface conditions, i.e. surface roughness, of powders were compared. The powders having rough surfaces show higher green strength than the round surface powders since higher roughness leads increasing interlocked area between the contacting powders.