단층대에서의 열-수리적 거동 모델링

이영민,김종찬,구민호,김영석,Lee, Young-Min,Kim, Jong-Chan,Koo, Min-Ho,Keehm, Young-Seuk 대한자원환경지질학회 2009 자원환경지질 Vol.42 No.6

지층 내에 발달한 고투수성 단층은 유체, 에너지, 그리고 용질이 이동하는데 있어서 중요한 역할을 하는 지질구조이다. 따라서 고투수성 단층 주변부에서는 지열수(혹은 온천), 지열 이상대, 그리고 금속 광상 등이 형성될 가능성이 크다. 단층의 구조에 따른 지하수 유동과 이에 따른 지층 내의 열적 상태를 확인하기 위해서 단층 구조가 다른 세 가지의 경우에 대해서 이차원 열-수리적 거동 모델링을 수행하였다. 모델링 결과로부터 세 가지 모든 단층 구조의 경우에서 단층의 투수율이 커지면 단층대에서의 지하수 용출 온도가 초기 온도 보다 높아지는 경향을 확인 할 수 있다. Peclet number 와 단층대에서의 용출온도의 상관관계 분석으로부터 상관계수($R^2$)가 0.98로 상당히 높은 것을 확인하였다. Peclet number가 1이상 일 때 단층대에서는 약 $32^{\circ}C$ 이상의 온도가 용출되며 이러한 경우에 단층대에서의 열흐름은 매질을 통한 전도 보다는 지하수에 의한 대류의 영향이 큰 것으로 판단된다. High permeable faults are important geological structures for fluid flow, energy, and solute transport. Therefore, high permeable faults play an important role in the formation of hydrothermal fluid (or hot spring), high heat flow, and hydrothermal ore deposits. We conducted 2-D coupled thermal and hydraulic modeling to examine thermohydraulic behavior in fault zones with various permeabilities and geometric conditions. The results indicate discharge temperature in fault zones increases with increasing fault permeability. In addition, discharge temperature in fault zones is linearly correlated with Peclet number ($R^2=0.98$). If Peclet number is greater than 1, discharge temperature in fault zones can be higher than $32^{\circ}C$. In this case, convection is dominant against conduction for the heat transfer in fault zones.

발아녹미와 노루궁뎅이 버섯 균사체를 이용한 생물전환 약용 신소재의 항산화 활성 및 NO 생성 억제 효능

이영민,김인숙,미툰 고쉬,홍성민,이택환,이동희,임병우,Lee, Young Min,Kim, In Sook,Ghosh, Mithun,Hong, Seong Min,Lee, Taek Hwan,Lee, Dong Hee,Lim, Beong Ou 한국약용작물학회 2017 한국약용작물학회지 Vol.25 No.5

Background: Hericium erinaceus is considered a functional food and potential medicinal source. The present study was conducted to examine the potential antioxidant and anti-inflammatory activities of carried out with water and ethanol extracts of Hericium erinaceus grown on germinated green rice (HEGR-W and HEGR-E, respectively) and the water and ethanol extracts of germinated green rice (GR-W and GR-E, respectively) as potential medicinal resources or antioxidant and anti-inflammatory agents. Methods and Results: The total phenolic and flavonoid contents, DPPH, and ABTS activity, reducing power, DNA protective activity, cell viability, and NO production were investigated. The total phenolic and flavonoid contents were highest in HEGR-E ($66.53{\pm}2.40 mg{\cdot}GAE/100g$ and $82.12{\pm}7.10mg{\cdot}CE/100g$ respectively). HEGR-E exhibited high DPPH ($44.70{\pm}1.28%$) and, ABTS ($44.70{\pm}1.28%$) activity and reducing power (0.219). HEGR and GR extracts showed protective activity against DNA damage. The cytotoxicity of HEGR and GR in RAW264.7 cells and LPS-induced RAW264.7 cells was low. HEGR-E and GR-W exhibited anti-inflammatory effects through a 28% inhibition of NO production in LPS-induced RAW264.7 cells. Conclusions: These results suggested that the extracts of Hericium erinaceus grown on germinated green rice could be a potential medicinal material with natural antioxidant and NO inhibitory properties.

상용차 오일압력 측정용 압력센서 제작을 위한 레이저용접기술

이영민,김순동,최해운,Lee, Young-Min,Kim, Soon-Dong,Cho, Hae-Woon 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.4

Using a fiber laser heat source, an oil pressure sensor was fabricated to measure the pressure in commercial vehicles. A stepping motor was used for the rotational and translational motion in the diaphragms and hardware joining. Laser welding process algorism including shielding gas control and vision system was integrated by using LabVIEW software for the high quality welding and in-line monitoring purpose. For the maximum flexibility in pressure transmission to the pressure sensor, thin sheet metal diaphragm, $25{\sim}50{\mu}m$(SUS-316L), was used and the diaphragms were optimally designed with FEM analysis. The welded samples were cross-sectioned the observation showed that the maximum depth ratio was more than seven times of diaphragms. The maximum welding speed was measured to be as high as 50in/mm by the developed automation mechanism. The fabricated prototypes were tested for the proof pressure, spring constant and sealing. The FEM results of spring constant measurement was as accurate as up to 80% of the design value and the sensor was safely operated up to the nominal pressure of 10bars.

벤처캐피탈 투자를 유치하는 신기술기반 벤처기업의 긍정 신호에 관한 연구 : 인적 자본과 전략적 보증효과에 관한 탐구

이영민,최영근,Lee, Young Min,Choi, Yeounkeun The Korean Society of Business Venturing 2014 벤처창업연구 Vol.9 No.6

본 연구는 신기술기반 벤처기업이 국내 벤처캐피탈의 투자를 유치하기 위한 인적 자본과 전략적 제휴의 보증효과 관계를 규명하였다. 벤처기업의 인적 자본과 외부 전략적 제휴가 벤처캐피탈에게 투자에 관한 긍정적인 신호 효과를 유발하는가와 함께 벤처캐피탈의 투자가 벤처기업의 성장에 미치는 영향을 살펴 보았다. 연구를 위하여 신호이론을 기반으로 두 가지 접근방법을 적용하였다 먼저, 신기술기반 벤처기업의 내재가치와 국내 벤처캐피탈에게 보증효과를 주는 조직 신호가 무엇인지 탐구하였다. 그리고 성장하고 있는 신기술기반 벤처기업에 벤처캐피탈의 투자가 중추적인 역할을 하는 지 분석하였다. 이러한 가정을 아시아 개발도상국의 대표적인 사례에 해당하는 국내 신기술기반 벤처기업들에 적용하여 검증하였다. 인적 자본 변수에서 기업가의 관련 산업분야 경험, 대기업의 비즈니스그룹과 협업 및 보증효과 변수에서 벤처기업의 인증은 벤처캐피탈의 투자를 유인하는 결과를 나타냈다. 반면에 창업자의 교육 수준은 벤처캐피탈의 투자유치 효과와 기업의 성장에 유의한 영향을 미치지 않는다는 결론을 도출하였다. In developing countries where many of these institutions exist in relatively weak form, the investment pattern of VCs in developing countries may differ from one of VCs in developed countries. Given this situation, the research question of this study is how venture capitals invest new technology based ventures in developing countries. To address the research question, our study employs insight from signaling theory and examines two ways. First, what are the internal value of new technology based ventures and the identity of endorsing organization signaling to venture capitals' investment in developing countries? Second, Do venture capitals play a pivotal role for the growth of new technology based ventures in developing countries? This study then tests these hypotheses using the new technology based ventures in Korea which is regarded as an example of developing countries in Northeas tern Asia. Entrepreneur's prior work experience in a related industry in the human capital variables and collaboration with business groups and certification of venture company in the endorsement variables result in obtaining venture capital's investment and superior new technology based venture's growth whereas entrepreneur's educational level has no effect on venture capital's investment and firm's growth.

ZTA에서 잔류응력이 파괴인성 증진에 미치는 영향

이영민,유진,Lee, Young-Min,Yu, Jin 한국세라믹학회 1990 한국세라믹학회지 Vol.27 No.3

In this investigation, bar-shaped specimens which consisted of three layers are prepared to study the effects of residual compressive stress on the mechanical properties in ZTA. The outer layers contained Al2O3 and unstabilized ZrO2 and the central layer contained Al2O3 and stabilized ZrO2(with 5.10wt% Y2O3). When cooled from the sintering temperature, some of zirconia in the outer layers transformed to the monoclinic form while zirconia in the central layer was retained in the tetragonal form. The transformation which induces to dilatational expansion led to the estabilishmenet of compressive stress in the outer layers and balances tensile stress in the central layer. Decrease of outer layer thickness(for a fixed total thickness)increases residual compressive stress. Because of residual compressive stress in the outer layers, the fracture toughness of outer layers of 3-layers composite is 10.21 Mpam1/2, which is increased to 25% above in comparison with 1-layer specimens in ZTA. Also, the 3-layers composite is believed to exhibite greater fracture resistance in contact damage environment from thermal shock test.

2단계 AlO_x 절연층 공정에서 하부절연층의 산화시간에 따른 터널자기저항 특성연구

이영민,송오성,Lee, Young-Min,Song, Oh-Sung 한국재료학회 2002 한국재료학회지 Vol.12 No.3

We fabricated TMR devices which have double oxidized tunnel barrier using plasma oxidation method to form homogeneously oxidized AlO tunnel barrier. We sputtered 10 $\AA$-bottom Al layer and oxidized it by varying oxidation time for 5, 10, 20 sec. Subsequent sputtering of 13 $\AA$ - Al was performed and the matallic layer was oxidized for 120 sec. The electrical resistance changed from 700$\Omega$ to 2700$\Omega$ with increase of oxidation time, while variation of MR ratio was little spreading 27~31% which is larger than that of TMR device of ordinary single tunnel barrier. We calculated effective barrier height and width by measuring I-V curves, from which we found the barrier height was 1.3~1.5 eV, sufficient for tunnel barrier, and the barrier width(<16.2 $\AA$) was smaller than that of directly measured value by the tunneling electron microscopy. Our results may be caused by insufficient oxidation of Al precursor into $Al_2O_3$. However, double oxidized tunnel barriers were superior to conventional single tunnel barrier in uniformity and density. We found that the external magnetic field to switch spin direction of ferromagnetic layer of pinned layer breaking ferro-antiferro exchange coupling was increased as bottom layer oxidation time increased. Our results imply that we were able to improve MR ratio and tune switching field by employing double oxidized tunnel barrier process.

타블렛 컴퓨터를 활용한 모바일 학습에 관한 학습자의 인식 조사

이영민,Lee, Young-Min 한국정보교육학회 2005 정보교육학회논문지 Vol.9 No.3

The purpose of the paper was to investigate students' perceptions of tablet computer-based mobile learning in a middle school. We examined the perceptions in terms of: 1) learning effectiveness, which refers to the effects of tablet computer on learning outcomes such as the grade; 2) attitude change, which is the change of students' attitudes and study habit; 3) learning activities, which refers to the kinds of learning activities using tablet computer; and 4) computer utilization, which is the ways of computer use in the study. The result showed that, in general, tablet computer affected all four types of perceptions positively.

오픈소스 소프트웨어의 선정 절차에 관한 연구

이영민,류성열,김종배,Lee, Young-Min,Rhew, Sung-Yul,Kim, Jong-Bae 한국정보처리학회 2008 정보처리학회논문지D Vol.15 No.6

소프트웨어의 품질, 개발 속도 및 비용 등 기존 소프트웨어 개발의 한계점을 해결하기 위한 새로운 대안으로써 오픈소스 소프트웨어를 활용한 개발 방법이 시도되고 있다. 특히, 중소기업들이 소프트웨어를 개발할 경우 대규모 개발 방법론 적용에 어려움을 겪고 있어 소규모 개발 방법에 대한 요구가 증가하고 있는 상황에서, 오픈소스를 활용한 소프트웨어 개발 방식은 비용을 절감하고 개발 기간을 단축시킬 수 있는 효율적인 방법이 될 수 있다. 이에 따라, 오픈소스 소프트웨어에 대한 다양한 분석들이 이루어졌지만 아직까지 산업현장에서 소프트웨어 개발에 오픈소스를 활용하기 위한 구체적인 절차나 방법이 없다. 본 연구에서는 이러한 문제들을 해결하기 위해 기존 연구에 대한 종합과 개발 프로젝트의 경험을 토대로 하여, 오픈소스의 식별과 선정을 위한 효과적인 절차와 방법을 제시하였다. 오픈소스 소프트웨어 선정을 위해서는 개발될 소프트웨어에 대한 정확한 요구사항을 식별하고, 요구사항과 일치하는 오픈소스를 조사하여 후보 목록을 추출하고, 평가기준을 수립하여, 이에 따라 활용 대상 오픈소스 소프트웨어를 선정하는 방법을 제시하였다. 또한 실제 프로젝트의 적용 실험과 평가를 통해 각 활동의 유효성과 개선점을 도출하였다. The development methods which utilize OSSs have been tried as new alternative to solve limits of the previous software developments such as the quality of software, and time and cost of developments. Especially, small and medium companies are suffering from difficulty in applying large-scale development methodology whenever they develop softwares. Therefore, in the current situation that demand for small-scale development methodology is increasing, the methods of utilizing OSSs can become an efficient way to save costs and reduce a development period. Accordingly, analysis of open-source is no fixed procedure or method to utilize open-source for software developments in the field. In this thesis, to solve such problems, we propose the procedures and methods for identifying and selecting suitable open-source, and effective methods for improvement and integration through least modification on the basis of synthesis of existing researches and experiences in development projects. For selection of OSSs, we did identify correct requirements for the software to be developed, investigate the open-source just matching with such requirements, draw a candidate index, establish assessment criteria, and the consequently present a method to select OSSs. And, we deduced the validity and improvement of each detailed activity from practical application to an actual project and assessment.

선형열처리를 이용한 Si(100)/Si$_3$N$_4$∥Si (100) 기판쌍의 직접접합

이영민,송오성,이상연,Lee, Young-Min,Song, Oh-Song,Lee, Sang-Hyun 한국재료학회 2001 한국재료학회지 Vol.11 No.5

절연 특성이 기존의 SiO$_2$ 보다 우수한 500 두께의 SiN$_4$층을 두 단결정 실리콘사이의 절연막질로 채택하고 직접접합시켜 직경 10cm의 Si(100) /500 -Si$_3$N$_4$/Si (100) 기판쌍을 제조하였다. p-type (100) 실리콘기판을 친수성, 소수성을 갖도록 습식방법으로 세척한 두 그룹의 시편들을 준비하였다. 기판전면에 LPCVD로 500 $\AA$ 두께의 Si$_3$N$_4$∥Si(100) 기판을 성장시키고 실리론 기판과 고청정상태에서 가접시킨 후, 선형열원의 이동속도를 0.1mm/s로 고정시키고 선형 입열량을 400~1125w 범위에서 변화시키면서 직접접합을 실시하였다. 접합된 기판은 적외선 카메라로 계면 접합면적을 확인하고 razor blade creek opening 측정법으로 세정 방법에 따른 각 기판쌍 그들의 접합강도를 확인하였다. 접합강도가 측정된 기판쌍은 high resolution transmission electron microscopy (HRTEM )을 사용하여 수직단면 미세구조를 조사하였다. 입열량의 증가에 따라 두 그를 모두 접합율은 큰 유의차 없이 765% 정도로, 소수성 처리가 된 기판쌍의 접합강도는 1577mJ/$m^2$가지 선형적으로 증가하였으나, 친수성 처리가 된 기판쌍은 주어진 실험 범위에서 입열량의 증가에 따라 큰 변화 없이 2000mj/$m^2$이상의 접합 강도를 보였다 친수성 처리가 된 기판쌍의 수직단면 미세구조를 고분해능 투과전자현미경으로 각인한 결과 모든 시편의 실리콘과 Si$_3$N$_4$사이에 25 $\AA$ 정도의 SiO$_2$ 자연산화막이 존재하여 중간충 역할을 함으로서 기판접합강도를 향상시키는 것으로 판단되었다. We prepared 10cm-diameter Si(100)/500 $\AA$-Si$_3$N$_4$/Si(100) wafer Pairs adopting 500 $\AA$ -thick Si$_3$N$_4$layer as insulating layer between single crystal Si wafers. Si3N, is superior to conventional SiO$_2$ in insulating. We premated a p-type(100) Si wafer and 500 $\AA$ -thick LPCVD Si$_3$N$_4$∥Si (100) wafer in a class 100 clean room. The cremated wafers are separated in two groups. One group is treated to have hydrophobic surface and the other to have hydrophilic. We employed a FLA(fast linear annealing) bonder to enhance the bond strength of cremated wafers at the scan velocity of 0.1mm/sec with varying the heat input at the range of 400~1125W. We measured bonded area using a infrared camera and bonding strength by the razor blade crack opening method. We used high resolution transmission electron microscopy(HRTEM) to probe cross sectional view of bonded wafers. The bonded area of two groups was about 75%. The bonding strength of samples which have hydrophobic surface increased with heat input up to 1577mJ/$m^2$ However, bonding strength of samples which have hydrophilic surface was above 2000mJ/$m^2$regardless of heat input. The HRTEM results showed that the hydrophilic samples have about 25 $\AA$ -thick SiO layer between Si and Si$_3$N$_4$/Si and that maybe lead to increase of bonding strength.

병렬처리 기법을 이용한 소형 무인비행체용 통합 시현 소프트웨어 플랫폼 개발

이영민,황인소,임배현,문용호,Lee, Young-Min,Hwang, In-So,Lim, Bae-Hyeon,Moon, Yong-Ho 대한임베디드공학회 2016 대한임베디드공학회논문지 Vol.11 No.1

An integrated display software platform for small UAV is developed based on parallel processing technique in this paper. When the small UAV with high-performance camera and avionic modules is employed to various surveillance-related missions, it is important to reduce the operator's workload and increase the monitoring efficiency. For this purpose, it is needed to develop an efficient monitoring software enable to manipulate the image and flight data obtained during flight within the given processing time and display them simultaneously. In this paper, we set up requirements and suggest the architecture for the software platform. The integrated software platform is implemented with parallel processing scheme. Based on AR drone, we verified that the various data are concurrently displayed by the suggest software platform.