진공사출금형용 STS316L 금속 다공체 제조 및 기계적 특성

김세훈,김상민,노상호,김진평,신재혁,성시영,진광진,김태안,Kim, Se Hoon,Kim, Sang Min,Noh, Sang Ho,Kim, Jin Pyeong,Shin, Jae Hyuck,Sung, Si-Young,Jin, Jin Kwang,Kim, Taean 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.3

In this study, porous stainless steel (STS316L) sintered body was fabricated by powder metallurgy method and its properties such as porosity, compressive yield strength, hardness, and permeability were evaluated. 67.5Fe-17Cr- 13Ni-2.5Mo (wt%) powder was produced by a water atomization. The atomized powder was classified into size with under $45{\mu}m$ and over $180{\mu}m$, and then they were compacted with various pressures and sintered at $1210^{\circ}C$ for 1 h in a vacuum atmosphere. The porosities of sintered bodies could be obtained in range of 20~53% by controlling the compaction pressure. Compressive yield strength and hardness were achieved up to 268 MPa and 94 Shore D, respectively. Air permeability was obtained up to $79l/min{\cdot}cm^2$. As a result, mechanical properties and air permeability of the optimized porous body having a porosity of 25~40% were very superior to that of Al alloy.

Nd-Fe-B 소결 자석의 보자력 향상

김세훈,김진우,변종민,김영도,Kim, Se Hoon,Kim, Jin Woo,Byun, Jong Min,Kim, Young Do 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.1

귀밑샘의 기무라병의 세침흡인 세포학적 소견 -세포학적 검사로 예측할 수 없었던 1예 보고-

김세훈,김혜령,김성은,양우익,이광길,홍순원,Kim, Se-Hoon,Kim, Hae-Ryoung,Kim, Sung-Eun,Yang, Woo-Ick,Lee, Kwang-Gil,Hong, Soon-Won 대한세포병리학회 2003 대한세포병리학회지 Vol.14 No.2

Kimura's disease is a chronic inflammatory disorder of unknown cause and is most prevalent among Asians. The cytologic findings of Kimura's disease are significant numbers of eosinophils in a background of lymphoid cells, occasional fragments of collagenous tissue, proliferation oi vessels, and Warthin-Finkeldey polykaryocytes. Among these features, the most important cytologic feature of Kimura's disease is a significant numbers of eosinophils. We experienced a case of Kimura's disease in the parotid gland which we fatted to recognize on cytology due to the apparent paucity of eosinophils. On careful retrograde reviewing of the cytologic findings, a few scattered leukocytes, previously interpreted as polymorphous leukocytes, had bilobed nuclei and coarse green but granular cytoplasm on Papanicolaou preparation. These leukocytes showed obvious orange-red intracyloplasmic granules as in eosionophils on Giemsa stain. The paucity of eosinophils may be due to the thick fibrosis around lymphoid follicles or any technical error during aspiration. Whereas the Warthin-Finkeldey type giant cell is not a sensitive cytologic marker of Kimura's disease, it may be a helpful cytologic feature. To reach a correct cytologic diagnosis of Kimura's disease, It is important to keep in mind that searching for Warthin-Finkeldey type giant cells and evaluation of Giemsa stain for detection of eosinophils would be helpful.

초미세 결정립을 가지는 몰리브덴의 제조 및 기계적 특성

김세훈,서영익,김대건,석명진,김영도,Kim, Se-Hoon,Seo, Young-Ik,Kim, Dae-Gun,Suk, Myung-Jin,Kim, Young-Do 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.3

Mo nanopowder was synthesized by ball-milling and subsequent hydrogen-reduction of $MoO_3$ powder. To fabricate ultra fine grained molybdenum, two-step sintering and spark plasma sintering process were employed. The grain size of specimen by two-step sintering and spark plasma sintering was around $0.6\;{\mu}m$ and $0.4\;{\mu}m$, respectively. Mechanical properties of ultra fine grained Mo with relative density of above 90% were significantly improved at room and high temperatures comparing to commercial bulk Mo of 99% relative density. This result was mainly explained by the grain size refinement due to diffusion-controlled sintering.

울금(鬱金)이 간성상세포의 섬유화 억제에 미치는 영향

김세훈,우홍정,김영철,이장훈,Kim, Se-Hoon,Woo, Hong-Jung,Kim, Young-Chul,Lee, Jang-Hoon 대한한방내과학회 2009 大韓韓方內科學會誌 Vol.30 No.2

Objectives : This study was performed to investigate the anti-fibrogenic effect of Curcumae Longae Radix on human hepatic stellate cells. Materials and Methods: Hepatic stellate cells (LX-2) were treated with various concentrations of Curcumae Longae Radix extract for 24, 48, and 72 hours. It was extracted with distilled water. After the treatment, cell viability, proliferation, cell cycle analysis, procollagen levels and the mRNA of the ASMA, TIMPl, TIMP2, MMP2, collagen type la, PDGF-receptor-beta and TGF-beta were measured by using MTT assay, BrdU assay, RT-PCR, and procollagen type 1 C-peptide EIA kit. Results : The viability of HSCs decreased in the 48 hours group, and proliferation of HSCs decreased as the concentration increased. In the cell cycle analysis, Curcumae Longae Radix decreased the ratio of M phase, and increased the ratio of apoptosis, G0/G1 and S phase. In the RT-PCR, the mRNA expression of the collagen type la and ASMA decreased with the Curcumae Longae Radix treatment. The production of procollagen by the HSCs was decreased by the treatment of Curcumae Longae Radix with high dose. Conclusion : These results suggest that Curcumae Longae Radix is helpful in the treatment of liver fibrosis as well as liver cirrhosis.

(Nd, Dy)-Fe-B 분말의 소결특성 및 상변화 연구

김세훈,김진우,김영도,Kim, Se-Hoon,Kim, Jin-Woo,Kim, Young-Do 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.2

In this study, the sintering behavior of (Nd, Dy)-Fe-B powder which fabricated by strip-casting was investigated with various sintering temperatures and holding times. The relative density over 99% could be obtained by both sintering at $1070^{\circ}C$ for 1h and sintering at $970^{\circ}C$ for 20h. The grain growth was observed in sintered specimen at $1050^{\circ}C$ compared to one at $970^{\circ}C$. The isothermal sintering process below $1000^{\circ}C$ led to suppress grain growth showing the improved magnetic properties. The phase transformation of Nd-rich was confirmed by X-ray diffraction pattern.

반복 열처리한 Nd-Fe-B 소결 자석의 미세구조 제어 및 자성특성 평가

김세훈,김훈섭,김동환,김영도,Kim, Se-Hoon,Kim, Hoon-Sup,Kim, Dong-Hwan,Kim, Young-Do 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.6

Sintered Nd-Fe-B magnets have been widely used due to their excellent magnetic properties, especially for driving motors of hybrid and electric vehicles. The microstructure of Nd-Fe-B magnets strongly affects their magnetic properties, in particular the coercivity. Therefore, a post-sintering process like heat-treatment is required for improving the magnetic properties of Nd-Fe-B sintered magnets. In this study, cyclic heat treatment was performed at temperatures between $350^{\circ}C$ and $450^{\circ}C$ up to 16 cycles in order to control microstructures such as size and shape of the Nd-rich phase without grain growth of the $Nd_{2}Fe_{14}B$ phase. The 2 cycles specimen at this temperature range showed more homogeneous microstructure which leads to higher coercivity of 35 kOe than as-sintered one.

피로를 주소로 내원한 환자의 생활섭생, 허손 및 피로의 상관성에 대한 고찰

김세훈,이장훈,이승보,최미영,김영철,우홍정,Kim, Se-Hoon,Lee, Jang-Hoon,Lee, Seung-Bo,Choi, Mi-Young,Kim, Young-Chul,Woo, Hong-Jung 대한한방내과학회 2008 大韓韓方內科學會誌 Vol.29 No.1

Objectives : Consumption is a chronic wasting disease, in oriental medicine concept. Fatigue is a common symptom experienced by many people who have consumption. However, there has been little study about the relationship between consumption and fatigue in the Oriental medicine. For this reason, we attempted to investigate the present status of fatigue of outpatients, and its relation with consumption index, public health practice index, Chalder fatigue scale and Subjective Symptoms of Fatigue Test. Methods : The subjects were 149 outpatients who complain fatigue between Nov. 1, 2006 and Oct. 31, 2007. We measured degree of consumption by consumption index. We measured degree of fatigue by Chalder fatigue scale and Subjective Symptoms of Fatigue Test. Public health practice were investigated by "Breslow's 7 health practice". Results : Studies have shown that a group who disregard public health practices have higher numerical value, in part of $q\grave{i}-x\bar{u}$, $xu\grave{e}-x\bar{u}$, and Physical symptoms than a group more concerned with public health practice. A group who has fatigue for a period over 6 months are more likely to be $q\grave{i}-x\bar{u}$, $y\bar{i}n-x\bar{u}$, Chalder fatigue scale, neuro-sensory symptoms than a group fatigued for less than 6 months. Among the subjects, 81 (55.5%) were considered as 'fatigue patients' by the Chalder scale. Chalder fatigue scale, according to the Subjective Symptoms of Fatigue Test, consumption also, The more increase of Subjective symptoms of fatigue test, the more of consumption scale. Conclusions : This study has shown that there is a link between consumption and fatigue. Moreover, oriental medicine's consumption is more concrete than fatigue scale, so consumption index will have wide application to the study of fatigue.

Primary Non-Hodgkin's Lymphomas Presenting with Extradural Spinal Cord Compression as the Initial Manifestation

김세훈,임동준,조태형,박정율,정용구,이훈갑,이기찬,서중근,Kim, Se Hoon,Lim, Dong Jun,Cho, Tai Hyoung,Park, Jung Yul,Chung, Yong Gu,Lee, Hoon Kap,Lee, Ki Chan,Suh, Jung Keun The Korean Neurosurgical Society 2000 Journal of Korean neurosurgical society Vol.29 No.10

악성 임파종중에서 Non-Hodgkin 임파종이 척수 압박 증상을 일으키는 경우는 0.1~10.2%정도로 알려져 있으며, 이러한 척수 압박 증세가 임파종의 초기 증상으로 나타나는 경우는 특히 드문 것으로 알려져 있다. 척수 압박은 척추관내에 국한되어 있는 임파종에 의하거나 주변 임파절이나 척추로부터 전이된 경우에 발생하며, 다른 장기로의 침범 소견이 없는 원발성 척수 경막외 임파종의 경우, 조기에 외과적 감압이 이루어지고 보조요법으로 항암 치료 및 방사선 치료가 행해진다면 그 경과가 비교적 양호한 것으로 알려져 있다. 저자들은 요통을 전구 증상으로, 급성 하반신 부전마비 및 배뇨 장애 소견을 보여 본원에 내원후, 응급 감압술 및 조직병리검사 결과 B-세포성 Non-Hodgkin 임파종으로 확인된 두 명의 여자환자를 경험하였다. 수술후 두 환자의 증세는 모두 회복되었으며, 항암 치료 및 방사선 치료후 현재까지 추적 조사중이다. 이에 저자들은 초기 증상으로 경막외 척수 압박을 보인 원발성 Non-Hodgkin 임파종에 관해 문헌 고찰과 함께 보고하는 바이다. Objectives : Spinal cord compression is a rare presentation of non-Hodgkin's lymphoma(NHL), occurring in 0.1% to 10.2% of patients. Primary spinal extradural NHL, i.e. occurring in the absence of any detectable extraspinal lymphoproliferative disorder, has a potentially favourable outcome if diagnosed and treated early. The authors describe two patients with a clinical picture of acute spinal cord compression as the first presentation of NHL. Methods : The patients were 48-year-old female and 27-year-old female. Both presented with back pain followed by acute paraparesis and voiding difficulty. One patient was diabetic. Plain radiographs of the spine were not specific. Thoracic spine magnetic resonance imaging(MRI) revealed evidence of extradural soft tissue mass extending multiple vertebral segments. Results : The patients underwent emergency laminectomy for decompression and tissue diagnosis. Histological and immunohistochemical study revealed B-cell lymphoma, intermediate grade in both patients. Postoperative staging did not reveal any additional lesions other than extradural manifestation of the malignant lymphoma. Surgery with additional chemotherapy and radiotherapy allowed the clinical improvement of both patients. Conclusion : The authors report two patients with a clinical picture of acute spinal cord compression as the first presentation of NHL, and stress that primary spinal epidural NHL should be a diagnostic consideration in the patient without prior history of malignancy who presents with a prodrome of back pain followed by a rapid neurological deterioration.

크리프 회복 거동을 고려한 철근콘크리트 및 프리스트레스트 콘크리트 부재의 장기거동해석에 관한 연구

김세훈,오병환,Kim, Se-Hoon,Oh, Byung-Hwan 한국콘크리트학회 1999 콘크리트학회지 Vol.11 No.1

콘크리트 구조물의 크리프해석은 주로 크리프식의 중첩원리에 기초한 방법에 의해 수행되고 있다. 그러나 크리프식의 중첩을 응력이 증가하거나 일정할 경우에는 비교적 정확한 예측이 가능하지만, 응력이 감소하는 경우에는 상당한 오차를 나타낸다. 이것은 지속하중과 응력감소 과정에서 크리프와 관련된 콘크리트의 성질이 변화되므로 크리프 회복을 크리프 식의 중첩으로 정확하게 모사할수 없기 때문이다. 따라서, 본 연구에서는 감소와 증가를 반복하는 응력 이력을 지니는 콘크리트 구조물의 좀더 정확하고 합리적인 장기거동 해석을 위하여 응력의 감소를 단순히 크리프식의 중첩에 의해 해석한 기존의 방법과는 달리 크리프식과 크리프 회복식으로 표현하여, 소위 2함수 방법(two-function method)를 콘크리트구조물의 해석에 적용하는 방법을 제시하였다. 본 연구의 2함수방법을 콘크리트 구조물의 장기거동 해석을 적용하기 위해, 시간단계 동안 다양한 응력 변화에 대하여 크리프 변형도 증분량을 계산하는 방법을 제시하였다. 본 연구의 해석방법에 의해서 해석된 결과를 기존의 크리프식의 중첩에 의한 결과 및 기존의 실험결과들과 비교 분석한 결과, 기존의 중첩법은 실험결과와 많은 차이를 보이고 있으나 본 연구의 해석방법은 실험결과와 잘 맞고 있음을 보여주고 있다. 따라서, 크리프회복식을 이용하는 본 연구의 해석방법은 기존의 크리프식의 중첩방법이나 기존의 설계기준에 비해 변화하는 응력이력 하에서의 콘크리트 구조물의 크리프거동을 더 정확하게 서술할 수 있는 방법으로서 앞으로 설계기준 작성과 실제 구조물 해석에 효율적인 응용이 기대되고 있다. The creep of concrete structures caused by variable stresses is generally calculated by step-by-step method based on the superposition of creep function. Although most practical application is carried out by this linear assumption. significant deviations between predictions and experiments have been observed when unloading takes place, that is. stress is reduced. This shows that the superposition of creep function does not describe accurately the effect of sustained compressive preload. The main purpose of this study is to propose a creep analysis model which is expressed with both creep function and creep recovery function where increase or decrease of stress is repeated. In these two function method, the creep behavior is modelled by using linear creep law for loading and creep recovery law for unloading. To apply two function method to time analysis of concrete structures, the calculation method of creep strain increment under varying stress is proposed. The calculation results based on the present method correlates very well with test data, but the conventional superposition method exhibits large deviation from test results. This paper provides a more accurate method for the time dependent analysis of concrete structures subjected to varying stress, i.e. increasing or decreasing stress. The present method may be efficiently employed in the revision of future concrete codes.