• Journal of the Korean Vacuum Society
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• v.22 no.1
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• pp.37-44
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• 2013

In order to investigate an influence of carrier trap by quantum dots (QDs) on the solar parameters, in this study, the $p^+-QD-n/n^+$ solar cells with InAs/GaAs QD active layers are fabricated, and their characteristics are investigated and compared with those of a GaAs matrix solar cell (MSC). Two different types of QD structures, the Stranski-Krastanow (SK) QD and the quasi-monolayer (QML) QD, have been introduced for the QD solar cells, and the parameters (open-circuit voltage ($V_{OC}$), short-cirucuit current ($I_{SC}$), fill factor (FF), conversion efficiency (CE)) are determined from the current-voltage characteristic curves under a standard solar illumination (AM1.5). In SK-QSC, while FF of 80.0% is similar to that of MSC (80.3%), $V_{OC}$ and $J_{SC}$ are reduced by 0.03 V and $2.6mA/cm^2$, respectively. CE is lowered by 2.6% as results of reduced $V_{OC}$ and $J_{SC}$, which is due to a carrier trap into QDs. Though another alternative structure of QML-QD to be expected to relieve the carrier trap have been firstly tried for QSC in this study, it shows negative results contrary to our expectations.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.6
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• pp.11-18
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• 2018

Isogeometric concept is introduced to find out the optimum layout of plane structure under free vibration. Eigenvalue problem is formulated and numerically solved in order to obtain natural frequencies and mode shapes of plane structures. For the exact geometric expression of the structure, the Non-Uniform Rational B-spline Surface (NURBS) basis functions is employed and it is also used to define the material density functions. A node-wise design variables is adopted to deal with the updating of material density in topology optimization (TO). The definition of modal strain energy is employed to achieve the maximization of fundamental frequency through its minimization. The verification of the proposed TO technique is performed by a series of benchmark test for plane structures.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.3-10
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• 2018

Damage location and extent of structure could be detected by the inverse analysis on dynamic response properties such as frequencies and mode shapes. In practice the measured difference of natural frequencies represent the stiffness change reliably, however the measured mode shape is insensitive for stiffness change, but provides spatial information of damage. The damage detection index on shear building structures is formulated in this study. The damage detection index could be estimated from mode shape and srory stiffness of undamaged structure and frequency difference between undamaged and damaged structure. For the verification of the observed damage detection method, the numerical analysis of Matlab and MIDAS and shacking table test were performed. In results, the damage index of damaged story was estimated so higher than undamaged stories that indicates the damaged story apparently.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.499-503
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• 2019

Characteristics of solar cells employing a lattice matched GaInP/GaAs quantum well (QW) structure in a single N-AlGaInP/p-InGaP heterojunction (HJ) were investigated and compared to those of solar cells without QW structure. The epitaxial layers were grown on a p-GaAs substrate with $6^{\circ}$ off the (100) plane toward the <111>A. The heterojunction of solar cell consisted of a 400 nm N-AlGaInP, a 590 nm p-GaInP and 14 periods of a 10 nm GaInP/5 nm GaAs for QW structure and a 800 nm p-GaInP for the HJ structure (control cell). The solar cells were characterized after the anti-reflection coating. The short-circuit current density for $1{\times}1mm^2$ area was $9.61mA/cm^2$ for the solar cell with QW structure while $7.06mA/cm^2$ for HJ control cells. Secondary ion mass spectrometry and external quantum efficiency results suggested that the significant enhancement of $J_{sc}$ and EQE was caused by the suppression of recombination by QW structure.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.5
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• pp.3-11
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• 2018

Since the tensegrity structure is flexible and variable, the study on the mobility to the tensegrity has been conducted. However, it is difficult to apply the tensegrity to the architecture field due to several limits. This paper describes the methodology for the analysis of the shape change process of single prism tensegrity structure as an initial study. To apply the tensegrity structure to the architectural field, the assemblage and mathematical formulation procedures of the single prism tensegrity structures are carried out. And single prism tensegrity are presented to the computational strategies for simulate the shape change of those structures. Next, the investigation of structural behaviors through various cases of target displacements is described. Also, the summary of these methods in algorithms is illustrated. As a result it is confirmed that the single prism tensegrity structure model converges 99% on average to a given target node by using the proposed algorithm. Therefore, it is confirmed that the proposed algorithm and program are suitable for shape change analysis of single prism tensegrity structure model.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.345-352
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• 2004

There are two paradigms to explain the atopic dermatitis. The first is outside-inside paradigm and the second is inside-outside paradigm. According to the outside-inside paradigm the best way to treat the atopic dermatitis is recovery of skin barrier function. The barrier function is maintained by the specific structure of stratum corneum, which is constructed from corneocytes and intercellular lipids. In terms of lipid structures of SC in atopic dermatitis and lamellar ichthyosis, they contain more fluid hexagonal gel structures in SC and show deficiencies in free fatty acids, especially long chains and certain ceramides. With this reason, moisturizer which has the lamellar structure and restoring function of intrinsic intercellualr long periodicity phase can maintain and restore the lamellar structure of intercellular lipids in SC. The moisturizers containing ceramide or pseudoceramide also seem to be reasonable therapy for atopic dermatitis and several skin diseases, which interrelated with impaired skin harrier. By the way, according to the inside-outside paradigm, immune response including helper T cells, IgE, eosinophils is related. It is effective treatment of atopic dermititis to restore imbalance between Th1 and Th2 cells. Even though several kinds of immune-suppressor were introduced, these can affect the intrinsic immune function. SPC and S1P, metabolites of ceramide, would be interesting because they have the function of wound healing and immune modulating properties.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1115-1120
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• 2017

In this paper, we apply the LMMSE(: Linear Minimum Mean Square Error) algorithm to overcome the Doppler effect according to the UAV(: Unmanned Aerial Vehicle) velocity in multipath fading channel environment. Simulation results show that the performance difference depends on the pilot arrangement and pattern, and we confirmed that the frame structure proposed in this paper can provide a stable secondary link for high speed UAV system.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.27-32
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• 2018

This work provides the analytical methods to represent the updated form of stiffness or flexibility matrices using the measurements of the first few natural frequencies and the corresponding mode shapes. This study derives the mathematical forms on the variance of stiffness or flexibility matrices to minimize the performance index in the satisfaction of the eigen-function including the residual force depending on the measured data. The proposed methods can be utilized in detecting damage and updating the parameter matrices deviated from the analytical parameter matrices. The validity of the proposed methods is investigated in a numerical experiment of truss structure and the numerical results of stiffness-based and flexibility-based methods are compared. The sensitivity to the external noise is also examined for applying to the practical work.

• Journal of Distribution Science
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• v.13 no.11
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• pp.111-121
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• 2015

Purpose - This study's purpose is to investigate the impact of supply chain management (SCM) factors among targeted Korean distribution firms. Antecedents are established for supply chain orientation (SCO) for the management and organization of cultural assets. The research sets up SCO corresponding to management cultural assets and to organizational factors in the results. The research model is created to examine the SCO based on a strategic perspective and the operational performance of the SC and SCM. In addition, an integrated model is constructed to analyze the moderating effect by setting partner cooperation as a relational capital factor. The main aim of this study is to analyze the characteristics of the supply chain structure as a source of competitive advantage for distribution service firms participating in the supply chain. In the moderating effects analysis, the role of partner cooperation as relational capital is examined in detail. Research design, data, and methodology - The study examined the existing research related to supply chains, discussing the antecedents of the performance of SCM and SCO. SCM was established with the partner's cooperation as relational capital. Including the moderating effects of the partner cooperation, the research proposed a seven hypotheses path analysis model. The samples were collected from the Korean export enterprises in the distribution service sector, with 185 samples selected for the final analysis. To try and measure the four latent variables presented in the analysis model based on existing studies, 22 measurement items were used. The empirical analysis used the appropriate PLS (partial least squares) method on the path analysis reliability and validity and for common method bias. After testing the seven hypotheses, the research tested the moderating effects to the path analysis. Using PLS as structural equation modeling, the seven hypotheses were tested including the moderating effects of the partner relational capital on the 185 samples. Results - In the results, the SCO had a positive impact on both SCM and the relational capital of partner cooperation. The SCM had a significant impact on the operational performance of the SC. Further, partner cooperation also had a significant impact on SCM and the operational performance of the SC. The moderating effect analysis of the SCM and partner cooperation found a significant impact on the operational performance of the SC. On the other hand, the moderating effect of the SCO and partner cooperation did not affect the SCM. Conclusion - The results of this research show that the existing supply chain-related research can be applied to the operational performance of the SC for a Korean distribution service firm. In view of the fact that SCO is a source of competitive advantage, it should be taken into account when a firm wants to improve the performance of the SCM of the distribution service. This is because it can be assumed that SCO plays a role in supply chain management for the distribution firm.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.2
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• pp.63-67
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• 2010

The organic solar cells with Glass/ITO/PEDOT:PSS/P3HT:PCBM/Al structure were fabricated using regioregular poly (3-hexylthiophene) (P3HT) polymer:(6,6)- phenyl $C_{61}$-butyric acid methyl ester (PCBM) fullerene polymer as the bulk hetero-junction layer. The P3HT and PCBM as the electron donor and acceptor materials were spin casted on the indium tin oxide (ITO) coated glass substrates. The optimum mixing concentration ratio of photovoltaic layer was found to be P3HT:PCBM = 4:4 in wt%, indicating that the short circuit current density ($J_{SC}$), open circuit voltage ($V_{OC}$), fill factor (FF) and power conversion efficiency (PCE) values were about 4.7 $mA/cm^2$, 0.48 V, 43.1% and 0.97%, respectively. To investigate the effects of the post annealing treatment, as prepared organic solar cells were post annealed at the treatment time range from 5min to 20min at $150^{\circ}C$. $J_{SC}$ and $V_{OC}$ increased with increasing the post annealing time from 5min to 15min, which may be originated from the improvement of the light absorption coefficient of P3HT and improved ohmic contact between photo voltaic layer and Al electrode. The maximum $J_{SC},\;V_{OC}$, FF and PCE values of organic solar cell, which was post annealed for 15min at $150^{\circ}C$, were found to be about 7.8 $mA/cm^2$, 0.55 V, 47% and 2.0%, respectively.