• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.101.1-101.1
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• 2016

Van der Waals (vdW) heterostructures built from two-dimensional layered materials provide an unprecedented opportunity in designing new material systems because the lack of dangling bonds on the vdW surfaces enables the creation of high-quality heterointerfaces without the constraint of atomically precise commensurability. In particular, the ability to build artificial heterostructures, combined with the recent advent of transition metal dichalcogenides, allows the fabrication of unique semiconductor heterostructures in an ultimate thickness limit for fundamental studies as well as novel device applications. In this talk, we will present the characterization of the electronic and optoelectronic properties of atomically thin p-n junctions consisting of vertically stacked WSe2 and MoS2 monolayers. We observed gate-tunable diode-like current rectification and a photovoltaic response across the p-n interface. Unlike conventional bulk p-n junctions, the tunneling-assisted interlayer recombination of the majority carriers is responsible for the tenability of the charge transport and the photovoltaic response. Furthermore, we will discuss the enhanced optoelectronic characteristics in graphene-sandwiched vdW p-n junctions.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.695-695
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• 2013

양단간의 온도차를 이용한 열전 발전 및 펠티어 효과를 이용한 열전냉각 소자는 전기와 열의 직접적인 변환으로 활용도가 높아 차세대 에너지 연구 분야로 각광 받고 있다. 열전 소자의 성능 척도는 성능지수 Z (Figure of Merit)로 나타내며, Seebeck 계수 및 전기전도도, 열전도도의 관계로 주어지게 되고 재료의 물성치가 소자의 성능에 큰 영향을 주게 된다. 따라서, 열전재료의 성능을 높이는 연구가 활발히 진행되어 왔으며, 최근 에너지 밴드 구조를 조절하여 Seebeck계수의 향상을 시도하는 연구가 많이 진행되고 있다. 이는 페르미 레벨근처에 도핑 된 원자들이 Density of states에 추가로 준위를 형성하여 Seebeck 계수 향상을 가능하게 한다. 본 연구에서는 상온용 열전 물질인 $Bi_2Te_3$에 Iodine 도핑을 통한 열전 성능 변화를 고찰하고자 한다. $Bi_2Te_3$는 유기금속 화합물 증착 방법으로 성장하였고 기판으로 $4^{\circ}$기울어진 GaAs를 사용 하였다. 전기적 특성은 Seebeck 측정 및 Van der Pauw법에 의한 Hall measurement 방법으로 분석하였다.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.94-98
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• 2003

The microstructure of Sn1.8Bi0.8Cu0.6In alloys was evaluated at various aging time. The bumps of Sn1.8Bi0.8Cu0.6In alloys after reflowed at $250^{\circ}C$ were well-formed and had 260um height. The craters on the bumps, however, were observed. Intermetallic compounds formed on the interface between so]der and Cu/Ni UBM were consist of $(Cu,Ni)_6Sn_5$. As aging goes on up to 1000hours, the composition of Ni changed from $6.63\%$ at initial stage(as-reflowed) to $13.47\%$ at final stage(1000hours aging ). In addition, after 500hours aging, the floating of IMC to the solder was observed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.4
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• pp.195-202
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• 2000

Recently, wave dissipating structures with porosity are widely used to improve habor tranquility and to reduce the wave overtopping rate. In this study, hydraulic model tests were performed to examine hydraulic efficiency of slit caissons, igloo blocks, and hollow blocks. The model tests showed that slit caissons were the most effective in dissipating wave energy under moderate wave conditions. Slit caissons and igloo blocks showed no significant difference in reducing wave overtopping rate. Hallow blocks are less effective in reducing wave overtopping rate than slit caissons and igloo blocks lU1der higher wave energy conditions.

• Korean Journal of Crystallography
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• v.10 no.2
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• pp.130-135
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• 1999

The title compound consisting of a calix[4]arene molecule with four phenyl rings bridged by four methylene groups and arranged alternately in anti-orientation fashion, two 25,27-bis(1-pro-pyloxy) groups attached on the two lower rims of calix[4]arene, and crown-6 chain attached on the other set of lower rims of calix[4]arene offers a big cavity inside a molecule which might possess a potential for forming host-guest complexes. The molecular packing is accomplished by van der Waals forces.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.286.2-286.2
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• 2013

기존의 이온성 고분자-금속 복합체(IPMC)는 백금(Pt)전극을 이온성 전기활성 고분자(Ionic electroactive polymer)인 나피온에 무전해 도금으로 만들어졌다. 본 연구는 백금전극을 그래핀으로 대체하여 투명 이온성 고분자-그래핀 복합체(IPGC)를 제작하였다. 그래핀은 근적외선 화학기상증착법(NIR-CVD)으로 전이금속 (Cu, Ni) 위에 탄화수소 가스(CH4)를 이용하여 성장하였다. 전이 금속위에 성장된 그래핀을 나피온 양쪽면에 van der Waals 결합력을 이용하는 습식 전이공정으로 전극을 형성하였다. IPGC는 면 저항(4-point probe), 투과도(UV/Vis spectrometer) 및 라만 분광법(Micro Raman spectroscopy)의 측정으로 그래핀 전극의 특성평가를 하였고, 전계방사 주사전자현미경(Field Emisson Scanning Electron Microscope; FE-SEM)을 사용하여 IPGC의 구조적 특성을 확인하였다. 제작된 IPGC의 성능은 백금전극을 이용한 IPMC의 변위(displacement), 힘(force), 작동 주파수(Operating frequency) 분석을 통해 비교 평가하였다.

• Archives of design research
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• no.18
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• pp.99-110
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• 1996

For the purpose of sped fying the character of Italian furniture industry, it's very important to analyse environmental aspects, in other word s, infrastructure of the furniture industry. These conditions that regional si tuation and circumstances, small and medium size of company depending upon the fami Iy oriented craftsman ship, roles of producers who are very keen on technical innovation and improvement, distribu tion structure and production status etc, are important factors to understand environmental characters of the furniture industry. Moreover, existence of various design languges according to design activities by architects un der that industrial structure is also regarded as the characters of that furniture industry. Through understanding the characters of Italian furniture industry and the drivig force of the growth, I would I ike to propose a role model for our domestic furniture industry.

• Korean Institute of Interior Design Journal
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• v.15 no.5 s.58
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• pp.68-76
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• 2006

Frei Otto, who is called to be the father of the ecological architecture, has shaped a peculiar architectural form style. In distance from the formalistic persistence to the modernist form canon and the postmodern tendencies to the self-representation of architects, Frei Otto has taken a more fundamentalistic position. Through the interdisciplinary researches on the self-organizing processes in the nature and the technical world Frei Otto could reason with architects, engineers, biologists, historians and philosophers the principle and structure of the natural construction that is applicable to the morphological research and the architectural construction research. In the middle of his architectural and scientific works is the idea of 'the natural construction' situated, and the basic principle and instrument of this 'Die Prinzip der Selbstbildung, The Principle of Self-making'. Founding himself on this principle, Frei Otto seeks after the new architectural form that is light, natural, flexible and variable by reasoning the typical formation process which refers to the common denominator of the self-making processes in the nature, the technique and the architecture. Despite his architecture is to be called to the anonymous, his architectural vision is headed toward the rationalistic form in accord with the natural laws. This study is purposed to elucidate the constellation to which his scientific attempts belong and the theoretical and methodological foundations of his architecture of 'the natural construction'.

• Explosives and Blasting
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• v.14 no.2
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• pp.71-80
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• 1996

A series of nurmerical analysse for the earhtquake of Iran railway tunnles under construction by NATM(New Astrian Tunnelling Method) were careid out throuth a pseudo-dynamic analyses techique used in a FFM computer program, DWTAP(Daewoo Tunnel Analysis Program), and the results are described in the paper. The analyses were performErl for two case;one is for the primary supports and the other is for the rompletEd permanent roncrete lining. The horizontal and verical groW1d accelerations for the design were estimatEd as 0.34 g and 0.23 g, respectively based on the historical reismic rerords in the proj3et area and the empirical equations. The results show that the turmel would be safe W1der the anticipitOO earthquake motion with the permanent roncrete lining, but some minor cracks rnigt be developErl in the primary shotcrete lining without any significant structural damages.

• Journal of the Korean Chemical Society
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• v.39 no.5
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• pp.344-349
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• 1995

The crystal and molecular structure of the title compound has been determined from 2568 reflections collected on an automatic CAD4 diffractometer using graphite-monochromated $Mo-K\alpha$ radiation. The crystal is monoclinic system, space group $P2_1$ with unit cell dimensions $a=8.756(8)\AA$, $b=25.757(2)\AA$, $c=8.628(1)\AA$, $\beta=99.15(4)^{\circ}$, V= 1,921(2) ${\AA}^3$, Z=4, $D_C=1.336\;g/cm^3$, ${\mu}=1.54\;cm^{-1}\;and\;T=298^{\circ}K$. The final R factor was 0.051 for 2049 reflections over $3{\sigma}(Fο).$ The crystal has two asymmetric molecules in the unit cell. The arrangement of sulfon group was shown a distorted tetrahedron structure and N(6), N(6') atoms were deviated from the least-squares planes of the thiadiazine rings, respectively. The molecular packings in the unit cell are linked by the two intermolecular hydrogen bonds of N-H---O type and van der Waals forces.