(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.

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.

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.

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

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.

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.

화학레이저 구동용 이젝터 시스템 개발 (I) - 화학레이저 구동용 초음속 이젝터 설계 변수 연구 -

김세훈,권세진,Kim, Se-Hoon,Kwon, Se-Jin 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.12

It is essential to operate chemical lasers with supersonic ejector system as the laser output power goes up. In this research, ejector design parameter study was carried out for optimal ejector design through understanding the ejector characteristics and design requirements for chemical lasers operating. Designed ejector was 3D annular type with 2$^{nd}$ -throat geometry and pressurized air was used for primary flow. Ejector design was carried out with two steps, quasi-1D gas dynamics was used for first design and commercial code was used to verify the first design. In this study, to get the effect of ejector geometry on its performance, three cases of primary nozzle area ratio and 2$^{nd}$ -throat cross sectional area and two cases of 2$^{nd}$ -throat L/D ratio experiments were carried out. Primary and secondary pressures were measured to get the mass flow rate ratio, minimum secondary pressure, ejector starting pressure and unstarting pressure at every case. In the result, better performance than design level was shown and optimal ejector design method for chemical lasers was obtained.

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.

전문건설업 안전보건경영시스템 동향연구

김세훈,강휘진,Kim, Se-hoon,Kang, Hwi-jin 한국방재안전학회 2020 한국방재안전학회 논문집 Vol.13 No.1

전문건설 업체의 안전보건경영시스템 도입·구축·운용은 안전시스템 도입과 운영 과정에 소요되는 비용이 발생하는 문제가 있다. 그리고 건설 안전 분야 기술 인력을 보유하지 못한 열악한 환경에서 안전시스템 구축 및 인증 취득 및 정착으로의 선순환 체계 구축이 쉽지 않은 실정이다. 이 논문의 목적은 건설업 안전보건경영시스템 관련 문헌을 조사·검토하고 실태 등 다양한 연구 동향을 분석하는 데 있다. 이를 통하여 건설업 안전보건경영시스템 구축 및 인증을 취득하고자 하는 전문건설 업체와 인증 취득 후 사후심사 및 연장심사를 이행 중인 전문건설업체의 안전보건경영시스템 수준 향상을 위한 방안을 모색하는데 있다. The introduction, construction, and operation of the safety and health management system of specialized construction companies have a problem incurred in the cost of introducing and operating the safety system. In addition, it is difficult to establish a virtuous cycle system to build a safety system, obtain a certification, and settle in a harsh environment that does not have technical personnel in construction safety. The purpose of this paper is to investigate and review the literature related to the safety and health management system of the construction industry and to analyze various research trends such as the actual situation. Through this, it is to find ways to improve the safety and health management system level of specialized construction companies that want to build and obtain the safety and health management system of the construction industry and specialized construction companies that are carrying out the post-assessment and extension examination after obtaining the certification.

한국 중소기업의 베트남 투자 분석: T사의 사례연구를 통하여

김세훈,Kim, Kyungmi,박현준 한국국제경영관리학회 2018 국제경영리뷰 Vol.22 No.4

Korea`s shoe industry has been steadily growing since the 1920s due to cheap and abundant labor. However, since the 1980s, exports and original equipment maker (OEM) orders started to decline because of Korea's rising labor costs and price competitiveness with Southeast Asian neighbors like China, Vietnam, and Indonesia. Therefore, domestic shoe factories, which have failed to overcome the high labor costs since 1980 had to move production bases to China, Vietnam, and Indonesia where labor costs are low. Thus, this research explored a Korean footwear company called the T company which is a renown shoe manufacturing company in South Korea. By analyzing the Export-Import Bank of Korea, Korea Trade-Investment Promotion Agency (KOTRA), Vietnam National Statistical Office, and Vietnam Foreign Investment Agency, the research was to understand and examine the T company’s business strategy overbroad, especially in Vietnam. We explored the accumulated investment-related issues and changes in the Vietnamese market and business environment. Furthermore, we investigated strategies and plans for how to cope with this change. We analyzed and examined the T company's ownership, location, and internalization advantages, as an example, which based on the eclectic paradigm and economic trends of the Vietnamese government and the state of the footwear industry. Finally, we investigated the future investment trends by sector and region to assist potential companies in entering the prospective Vietnamese market. 한국의 신발산업은 1920년대 이후 저렴한 인건비 및 풍부한 노동력에 의해 지속적으로 성장을 했다. 그러나 1980년대 이후 한국의 인건비 상승과 동남아시아의 주변국인 중국, 베트남, 인도네시아와 가격 경쟁력에서 차이를 보이게 됨으로써, original equipment manufacturer (OEM) 주문량이 줄어들기 시작하고 수출액 또한 감소세에 이르게 되었다. 따라서 1980년 이후 높은 인건비의 벽을 넘지 못한 국내 신발 공장들은 인건비가 저렴한 중국, 베트남, 인도네시아로 생산 기반을 이전하게 되었다. 이를 바탕으로 본 연구는 한국수출입은행, 대한무역투자진흥공사(KOTRA), 베트남 통계청, 베트남 외국인 투자 청과 국내 중견기업인 T사의 지속가능경영보고서를 기반으로 경공업 분야에서 베트남에 진출하고자 하는 국내 제조업 분야 중소기업의 투자방안에 대해 분석하였다. 또한 이 연구는 그동안의 축적되어온 투자 관련 이슈와 베트남 시장 및 기업 환경의 변화 등에 대해 자세히 기술하고 있고 이 변화에 어떻게 대처하는가에 대한 전략과 방안을 논의하였다. T사의 사례연구를 통하여 한국 신발산업의 사업 현황과 베트남 경제 동향 및 신발산업을 비교 분석하여 베트남 진출에 있어 T사의 성공사례를 기반으로 향후 베트남 투자에 진출하고자 하는 기업에 도움이 되고자 한다.