• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.629-635
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• 2012

Two novel conjugated copolymers utilizing 4,7-dithien-2-yl-2,1,3-benzothiadiazole (DTBT) coupled with cyano (-CN) substituted vinylene, as the electron deficient moeity, have been synthesized and evaluated in bulk heterojunction solar cell. The electron deficient moeity was coupled with carbazole and fluorene unit by Knoevenagel condition to provide poly(bis-2,7-((Z)-1-cyano-2-(5-(7-(2-thienyl)-2,1,3-benzothiadiazol-4-yl)-2-thienyl)ethenyl)-alt-9-(1-octylnonyl)-9H-carbazol-2-yl-2-butenenitrile) (PCVCNDTBT) and poly(bis-2,7-((Z)-1-cyano-2-(5-(7-(2-thienyl)-2,1,3-benzothiadiazol-4-yl)-2-thienyl)ethenyl)-alt-9,9-dihexyl-9H-fluoren-2-yl) (PFVCNDTBT). The optical band gaps of PCVCNDTBT (1.74 eV) and PFVCNDTBT (1.80 eV) are lower than those of PCDTBT (1.88 eV) and PFVDTBT (2.13 eV), which is advantageous to provide better coverage of the solar spectrum in the longer wavelength region. The high $V_{oc}$ value of the PSC of PCVCNDTBT (~0.91 V) is attributed to its lower HOMO energy level ( 5.6 eV) as compared to PCDTBT ( 5.5 eV). Bulk heterojunction solar cells based on the blends of the polymers with [6,6]phenyl-$C_{61}$-butyric acid methyl ester ($PC_{61}BM$) gave power conversion efficiencies of 0.76% for PCVCNDTBT under AM 1.5, 100 mW/$cm^2$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.189-189
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• 2012

Lead sulfide (PbS) nanocrystal quantum dots (NQDs) are promising materials for various optoelectronic devices, especially solar cells, because of their tunability of the optical band-gap controlled by adjusting the diameter of NQDs. PbS is a IV-VI semiconductor enabling infrared-absorption and it can be synthesized using solution process methods. A wide choice of the diameter of PbS NQDs is also a benefit to achieve the quantum confinement regime due to its large Bohr exciton radius (20 nm). To exploit these desirable properties, many research groups have intensively studied to apply for the photovoltaic devices. There are several essential requirements to fabricate the efficient NQDs-based solar cell. First of all, highly confined PbS QDs should be synthesized resulting in a narrow peak with a small full width-half maximum value at the first exciton transition observed in UV-Vis absorbance and photoluminescence spectra. In other words, the size-uniformity of NQDs ought to secure under 5%. Second, PbS NQDs should be assembled carefully in order to enhance the electronic coupling between adjacent NQDs by controlling the inter-QDs distance. Finally, appropriate structure for the photovoltaic device is the key issue to extract the photo-generated carriers from light-absorbing layer in solar cell. In this step, workfunction and Fermi energy difference could be precisely considered for Schottky and hetero junction device, respectively. In this presentation, we introduce the strategy to obtain high performance solar cell fabricated using PbS NQDs below the size of the Bohr radius. The PbS NQDs with various diameters were synthesized using methods established by Hines with a few modifications. PbS NQDs solids were assembled using layer-by-layer spin-coating method. Subsequent ligand-exchange was carried out using 1,2-ethanedithiol (EDT) to reduce inter-NQDs distance. Finally, Schottky junction solar cells were fabricated on ITO-coated glass and 150 nm-thick Al was deposited on the top of PbS NQDs solids as a top electrode using thermal evaporation technique. To evaluate the solar cell performance, current-voltage (I-V) measurement were performed under AM 1.5G solar spectrum at 1 sun intensity. As a result, we could achieve the power conversion efficiency of 3.33% at Schottky junction solar cell. This result indicates that high performance solar cell is successfully fabricated by optimizing the all steps as mentioned above in this work.

• 펄프종이기술
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• 제29권1호
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• pp.73-83
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• 1997

Most of the materials used in various industrial fields and also in our daily life are multi-component materials or composite materials, and it is well known that there are many cases where adhesion between the constituents within the bonded systems plays an important role. There are various types of performance evaluation tests for the bonded materials, among which tests for evaluating the bond performance under various conditions may be regarded as the most interesting ones for those engaged in work related to adhesion. I have studied on the mechanism of adhesion form the rheological standpoint with my colleagues, including some students from Korea, and I am very happy to be able to have a talk on some of our research works. In Japan, the so-called "adhesives" are usually classified into two categories;adhesives and pressure sensitive adhesives (PSA). Adhesives are the materials which solidify after bonding and are after used as the structural adhesives because the adhesive strength is comparatively strong. On the other hand, the pressure sensitive adhesives never solidify and are used as PSA tapes, labels or decals. About the adhesives, we have examined the dependence of adhesive strength(shear, tensile, peel) upon both temperature and rate of deformation, and found out some empirical rules which are applicable to most of the adhesive systems. We have also developed a simplified theory of adhesion, which is deseribed in terms of mechanical equivalent mode1 and a few failure criteria. Although some of the common rules can be accounted for according to this theory, it must be pointed out that a fracture mechanical approach ms inevitable especially in the region where the meehanical relaxation time of the adhesive is extremely large [W. W. Lim and H. Mizumachi]. About the pressure sensitive adhesives, we have studied on the PSA performance (peel, tack, holding power) as a function of both the viscoelastic properties and surface chemical properties of the materials, and found out some rules, and again we have developed a theory which deseribes the mechanism. And in addition, we have studied on the miscibility between linear polymers and oligomers, because PSA is generally manufactured by blending gums and tackifier resins. Many phase diagrams have been found and some of them have been analyzed on thermodynamic basis, and it became evident that the miscibility is a very important factor in PSA [H. J. Kin and H. Mizumachi]. In this presentation, I want to emphasize the fact that the adhesion performance is closely related to the structure/property of the adhesives.adhesives.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2006년도 추계학술발표대회 논문집
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• pp.370-373
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• 2006

Lastly, the problem of filling occurs in the process of concealed joint of adjacent components and was seen in joints between the structure and an electrical or mechanical device. Therefore, the dry processing which replaces wet joint was seen in joints between the structure and a door, ones between the structure and a finishing materials, ones between a gypsum board and electrical device, and ones between a water pipe and a tile finishing. And a process of separating the area of jointed parts in order to eliminate the problem of overlap was seen in joints between a door and a finishing material and ones between a gypsum board on the ceiling and a light. Lastly, an analysis of a process of exposing concealed parts indicated that the problem of filling could be applied to joints between the structure and an electrical or mechanical device and ones between a finishing material and a mechanical device. This study sought out methods to apply Environment Friendly Multi Housing Remodeling that allow easy remodeling as part of environment- preserving policies. It also contains basic data useful to implement long-life houses in the future by presenting a comprehensive design standard for them

• Applied Microscopy
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• 제47권3호
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• pp.208-213
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• 2017

The microstructural changes in Co nanoparticles and an Au-10at.%Pd thin film have been investigated using an in situ heating holder with a micro-electro-mechanical system (MEMS). In Co nanoparticles, two phases (face-centered cubic and hexagonal close-packed crystal structures) were found to coexist at room temperature and microstructures at temperatures, higher than $1,000^{\circ}C$, were observed with a quick response time and significant stability. The actual temperature of each specimen was directly estimated from the changes in the lattice spacing (Bragg-peak separation). For the Au-10at.%Pd thin film, at a set temperature of $680^{\circ}C$, the actual temperature of the sample was estimated to be $1,020^{\circ}C{\pm}123^{\circ}C$. Note that the specimen temperature should be carefully evaluated because of the undesired effects, i.e., the temperature non-uniformity due to the sample design of the MEMS chip, and distortion due to thermal expansion.

• Applied Microscopy
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• 제47권3호
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• pp.187-202
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• 2017

The classical electron band theory is a powerful tool to describe the electronic structures of solids. However, the band theory and corresponding density functional theory become inappropriate if a system comprises localized electrons in a scenario wherein strong electron correlations cannot be neglected. $SrRuO_3$ is one such system, and the partially localized d-band electrons exhibit some interesting behaviors such as enhanced effective mass, spectral incoherency, and oppression of ferromagnetism and itinerancy. In particular, a Metal-Insulator transition occurs when the thickness of $SrRuO_3$ approaches approximately four unit cells. In the computational studies, irrespective of the inclusion of on-site Hubbard repulsion and Hund's coupling parameters, correctly depicting the correlation effects is difficult. Because the oxygen atoms and the symmetry of octahedra are known to play important roles in the system, scrutinizing both the electronic band structure and the lattice system of $SrRuO_3$ is required to find the origin of the correlated behaviors. Transmission electron microscopy is a promising solution to this problem because of its integrated functionalities, which include atomic-resolution imaging and electron energy loss spectroscopy.

• Applied Microscopy
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• 제47권1호
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• pp.36-42
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• 2017

Field electron emission measurements were performed on dielectric-coated tungsten emitters, with apex radii in the nanometer and micrometer range, which were prepared by electrochemical etching in NaOH solution. Measurements were performed in a field electron microscopy (FEM) with a base pressure <$10^{-6}$ Pascal ($10^{-8}$ mbar). Four different types of dielectric were used, namely: (1) Clark Electromedical Instruments epoxylite resin, (2) Epidian 6 produced by Ciech Sarzyna S. A., (3) a Radionox solution of colloidal graphite; and (4) Molyslip 2001 E compound ($MoS_2$ and MoS). Current-voltage measurements and FEM images were used to investigate the characteristics of these composite emitters, and to assess how the different types of dielectric coating affect the suitability of the composite emitter as a potential electron source.

• 패션비즈니스
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• 제2권2호
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• pp.11-25
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• 1998

The purpose of this paper is to investigate how the young fashion which maintains a large share of fashion market emerged in the 1960s, its characteristics and what its influences on the contemporary fashion industry are. In particular, I am going to consider the significance of the young fashion by looking at the formation of niche market, the emergence of mass market for fashion, the expansion of aesthetic categories. we will be able to see the 60s young fashion of the young generation who emerged as new consumers in mass consumer culture exerted important influences on the contemporary fashion industry. First, the counterculture of young generation who rebeled against the uniformity of mass production helped the formation of new niche market. Second, the young fashion which pursued the lower prices for fashion made a big contribution to the popularization of fashion. The young generations tendency to demand new things and rapid change coincided with that of inexpensive popular fashion people can buy and change more easily than expensive high fashion. Lastly, the playful tendency of the young fashion expanded the aesthetic boundaries of the clothing, going beyond the uniformity of modernism with the emergency of diverse fashion materials - fabric and textiles - enable by technological development and the miniaturization of forms as revealed in mini skirt.

• 한국의류학회지
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• 제34권10호
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• pp.1754-1766
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• 2010

Excessive consumption, pollution, and am expanding global population are seen as very important issues that must be solved through reusable materials and the reduction of energy consumption. This study examines the values and design elements such as line, color, and textures in eco-friendly fashion that could contribute to the product development of an eco-friendly brand. The following methods of analysis were used in this study. An in-depth interview (where the interviewer records the response of interviewers to questions) was used to grasp the diverse design properties of products that customers need or want and the recorded interviews were documented by computer using open coding. The results show that the personal, economic, and social value of eco-friendly fashion has increased, in addition to the environmental value. The needs and preference of customers for eco-friendly fashion design were diversified and the consumer consciousness was more advanced than the consciousness of experts. This shows that it is not enough to consider the effect on the environment. In conclusion, understanding the personal, environmental, economic, and social value from the viewpoint of customers, finding the optimal design factors, and reflecting them in the development of products are necessary for advanced eco-friendly fashion.

• 한국항해항만학회지
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• 제31권8호
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• pp.711-716
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• 2007

컨테이너에 화물을 적재함에 있어서 고려해야할 점으로 컨테이너의 적재율을 들 수 있다. 단순히 제한된 공간에 보다 많은 양의 화물을 적재하여 비용을 낮추고자 하는 노력은 꾸준히 계속되어 왔다. 하지만 방문순서를 고려해야만 하는 화물의 경우는 다르다. 조선기자재와 같은 대형 화물들의 경우 방문순서를 고려하지 않았을 경우 하역작업에서 화물 재 조작 또는 하역 작업이 불가능한 상황이 발생할 수 있기 때문이다. 본 연구에서는 화물 적재 시 방문 순서를 고려하는 문제를 해결하고자 하며, 이에 방문 순서와 적재율을 동시에 고려한 컨테이너 혼재모형과 그 해법을 제시하고자 한다.